RNA Polymerase II: A DNA-dependent RNA polymerase present in bacterial, plant, and animal cells. It functions in the nucleoplasmic structure and transcribes DNA into RNA. It has different requirements for cations and salt than RNA polymerase I and is strongly inhibited by alpha-amanitin. EC 2.7.7.6.Transcription, Genetic: The biosynthesis of RNA carried out on a template of DNA. The biosynthesis of DNA from an RNA template is called REVERSE TRANSCRIPTION.DNA-Directed RNA Polymerases: Enzymes that catalyze DNA template-directed extension of the 3'-end of an RNA strand one nucleotide at a time. They can initiate a chain de novo. In eukaryotes, three forms of the enzyme have been distinguished on the basis of sensitivity to alpha-amanitin, and the type of RNA synthesized. (From Enzyme Nomenclature, 1992).RNA Polymerase III: A DNA-dependent RNA polymerase present in bacterial, plant, and animal cells. It functions in the nucleoplasmic structure where it transcribes DNA into RNA. It has specific requirements for cations and salt and has shown an intermediate sensitivity to alpha-amanitin in comparison to RNA polymerase I and II. EC 2.7.7.6.RNA Polymerase I: A DNA-dependent RNA polymerase present in bacterial, plant, and animal cells. The enzyme functions in the nucleolar structure and transcribes DNA into RNA. It has different requirements for cations and salts than RNA polymerase II and III and is not inhibited by alpha-amanitin. EC 2.7.7.6.Transcriptional Elongation Factors: Transcription factors whose primary function is to regulate the rate in which RNA is transcribed.Amanitins: Cyclic peptides extracted from carpophores of various mushroom species. They are potent inhibitors of RNA polymerases in most eukaryotic species, blocking the production of mRNA and protein synthesis. These peptides are important in the study of transcription. Alpha-amanitin is the main toxin from the species Amanitia phalloides, poisonous if ingested by humans or animals.Transcription Factors, TFII: The so-called general transcription factors that bind to RNA POLYMERASE II and that are required to initiate transcription. They include TFIIA; TFIIB; TFIID; TFIIE; TFIIF; TFIIH; TFII-I; and TFIIJ. In vivo they apparently bind in an ordered multi-step process and/or may form a large preinitiation complex called RNA polymerase II holoenzyme.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.RNA: A polynucleotide consisting essentially of chains with a repeating backbone of phosphate and ribose units to which nitrogenous bases are attached. RNA is unique among biological macromolecules in that it can encode genetic information, serve as an abundant structural component of cells, and also possesses catalytic activity. (Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)Promoter Regions, Genetic: DNA sequences which are recognized (directly or indirectly) and bound by a DNA-dependent RNA polymerase during the initiation of transcription. Highly conserved sequences within the promoter include the Pribnow box in bacteria and the TATA BOX in eukaryotes.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Transcription Factors: Endogenous substances, usually proteins, which are effective in the initiation, stimulation, or termination of the genetic transcription process.Templates, Genetic: Macromolecular molds for the synthesis of complementary macromolecules, as in DNA REPLICATION; GENETIC TRANSCRIPTION of DNA to RNA, and GENETIC TRANSLATION of RNA into POLYPEPTIDES.Transcription Factors, General: Transcription factors that form transcription initiation complexes on DNA, bind to specific DNA-DIRECTED RNA POLYMERASES and are required to initiate transcription. Although their binding may be localized to distinct sequence and structural motifs within the DNA they are considered non-specific with regard to the specific gene being transcribed.Saccharomyces cerevisiae: A species of the genus SACCHAROMYCES, family Saccharomycetaceae, order Saccharomycetales, known as "baker's" or "brewer's" yeast. The dried form is used as a dietary supplement.HeLa Cells: The first continuously cultured human malignant CELL LINE, derived from the cervical carcinoma of Henrietta Lacks. These cells are used for VIRUS CULTIVATION and antitumor drug screening assays.RNA, Viral: Ribonucleic acid that makes up the genetic material of viruses.Transcription Factor TFIIB: An RNA POLYMERASE II specific transcription factor. It plays a role in assembly of the pol II transcriptional preinitiation complex and has been implicated as a target of gene-specific transcriptional activators.Transcription Factor TFIID: The major sequence-specific DNA-binding component involved in the activation of transcription of RNA POLYMERASE II. It was originally described as a complex of TATA-BOX BINDING PROTEIN and TATA-BINDING PROTEIN ASSOCIATED FACTORS. It is now know that TATA BOX BINDING PROTEIN-LIKE PROTEINS may take the place of TATA-box binding protein in the complex.TATA-Box Binding Protein: A general transcription factor that plays a major role in the activation of eukaryotic genes transcribed by RNA POLYMERASES. It binds specifically to the TATA BOX promoter element, which lies close to the position of transcription initiation in RNA transcribed by RNA POLYMERASE II. Although considered a principal component of TRANSCRIPTION FACTOR TFIID it also takes part in general transcription factor complexes involved in RNA POLYMERASE I and RNA POLYMERASE III transcription.Saccharomyces cerevisiae Proteins: Proteins obtained from the species SACCHAROMYCES CEREVISIAE. The function of specific proteins from this organism are the subject of intense scientific interest and have been used to derive basic understanding of the functioning similar proteins in higher eukaryotes.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.RNA, Messenger: RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.Dichlororibofuranosylbenzimidazole: An RNA polymerase II transcriptional inhibitor. This compound terminates transcription prematurely by selective inhibition of RNA synthesis. It is used in research to study underlying mechanisms of cellular regulation.Transcription Elongation, Genetic: The lengthening of a nascent RNA molecule by RNA POLYMERASE during transcription.DNA Polymerase II: A DNA-dependent DNA polymerase characterized in E. coli and other lower organisms. It may be present in higher organisms and has an intrinsic molecular activity only 5% of that of DNA Polymerase I. This polymerase has 3'-5' exonuclease activity, is effective only on duplex DNA with gaps or single-strand ends of less than 100 nucleotides as template, and is inhibited by sulfhydryl reagents. EC 2.7.7.7.Mediator Complex: A large protein complex which acts as a signaling adaptor protein that allows communication between the various regulatory and functional components of GENETIC TRANSCRIPTION including DNA POLYMERASE II; GENERAL TRANSCRIPTION FACTORS; and TRANSCRIPTION FACTORS that are bound to upstream ENHANCER ELEMENTS. The mediator complex was originally studied in YEAST where at least 21 subunits were identified. Many of the yeast subunits are homologs to proteins in higher organisms that are found associated with specific nuclear receptors such as THYROID HORMONE RECEPTORS and VITAMIN D RECEPTORS.Chromatin: The material of CHROMOSOMES. It is a complex of DNA; HISTONES; and nonhistone proteins (CHROMOSOMAL PROTEINS, NON-HISTONE) found within the nucleus of a cell.Protein Binding: The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.Transcription Factor TFIIH: A general transcription factor that is involved in basal GENETIC TRANSCRIPTION and NUCLEOTIDE EXCISION REPAIR. It consists of nine subunits including ATP-DEPENDENT DNA HELICASES; CYCLIN H; and XERODERMA PIGMENTOSUM GROUP D PROTEIN.RNA, Small Interfering: Small double-stranded, non-protein coding RNAs (21-31 nucleotides) involved in GENE SILENCING functions, especially RNA INTERFERENCE (RNAi). Endogenously, siRNAs are generated from dsRNAs (RNA, DOUBLE-STRANDED) by the same ribonuclease, Dicer, that generates miRNAs (MICRORNAS). The perfect match of the siRNAs' antisense strand to their target RNAs mediates RNAi by siRNA-guided RNA cleavage. siRNAs fall into different classes including trans-acting siRNA (tasiRNA), repeat-associated RNA (rasiRNA), small-scan RNA (scnRNA), and Piwi protein-interacting RNA (piRNA) and have different specific gene silencing functions.Polymerase Chain Reaction: In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships.Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.RNA Splicing: The ultimate exclusion of nonsense sequences or intervening sequences (introns) before the final RNA transcript is sent to the cytoplasm.Escherichia coli: A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.DNA-Directed DNA Polymerase: DNA-dependent DNA polymerases found in bacteria, animal and plant cells. During the replication process, these enzymes catalyze the addition of deoxyribonucleotide residues to the end of a DNA strand in the presence of DNA as template-primer. They also possess exonuclease activity and therefore function in DNA repair.TATA Box: A conserved A-T rich sequence which is contained in promoters for RNA polymerase II. The segment is seven base pairs long and the nucleotides most commonly found are TATAAAA.Cell Nucleus: Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (CELL NUCLEOLUS). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the ENDOPLASMIC RETICULUM. A cell may contain more than one nucleus. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)DNA: A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).RNA, Ribosomal: The most abundant form of RNA. Together with proteins, it forms the ribosomes, playing a structural role and also a role in ribosomal binding of mRNA and tRNAs. Individual chains are conventionally designated by their sedimentation coefficients. In eukaryotes, four large chains exist, synthesized in the nucleolus and constituting about 50% of the ribosome. (Dorland, 28th ed)Histones: Small chromosomal proteins (approx 12-20 kD) possessing an open, unfolded structure and attached to the DNA in cell nuclei by ionic linkages. Classification into the various types (designated histone I, histone II, etc.) is based on the relative amounts of arginine and lysine in each.RNA Replicase: An enzyme that catalyses RNA-template-directed extension of the 3'- end of an RNA strand by one nucleotide at a time, and can initiate a chain de novo. (Enzyme Nomenclature, 1992, p293)Positive Transcriptional Elongation Factor B: A transcriptional elongation factor complex that is comprised of a heterodimer of CYCLIN-DEPENDENT KINASE 9 and one of several CYCLINS including TYPE T CYCLINS and cyclin K. It functions by phosphorylating the carboxy-terminal domain of RNA POLYMERASE II.Cyclin-Dependent Kinase 9: A multifunctional CDC2 kinase-related kinase that plays roles in transcriptional elongation, CELL DIFFERENTIATION, and APOPTOSIS. It is found associated with CYCLIN T and is a component of POSITIVE TRANSCRIPTIONAL ELONGATION FACTOR B.Cyclin-Dependent Kinase 8: A CYCLIN C dependent kinase that is an important component of the mediator complex. The enzyme is activated by its interaction with CYCLIN C and plays a role in transcriptional regulation by phosphorylating RNA POLYMERASE II.TATA-Binding Protein Associated Factors: Factors that associate with TATA-BOX BINDING PROTEIN. Many of them are components of TRANSCRIPTION FACTOR TFIIDDNA-Binding Proteins: Proteins which bind to DNA. The family includes proteins which bind to both double- and single-stranded DNA and also includes specific DNA binding proteins in serum which can be used as markers for malignant diseases.Binding Sites: The parts of a macromolecule that directly participate in its specific combination with another molecule.Terminator Regions, Genetic: DNA sequences recognized as signals to end GENETIC TRANSCRIPTION.RNA, Small Nuclear: Short chains of RNA (100-300 nucleotides long) that are abundant in the nucleus and usually complexed with proteins in snRNPs (RIBONUCLEOPROTEINS, SMALL NUCLEAR). Many function in the processing of messenger RNA precursors. Others, the snoRNAs (RNA, SMALL NUCLEOLAR), are involved with the processing of ribosomal RNA precursors.Macromolecular Substances: Compounds and molecular complexes that consist of very large numbers of atoms and are generally over 500 kDa in size. In biological systems macromolecular substances usually can be visualized using ELECTRON MICROSCOPY and are distinguished from ORGANELLES by the lack of a membrane structure.RNA, Fungal: Ribonucleic acid in fungi having regulatory and catalytic roles as well as involvement in protein synthesis.Chromatin Immunoprecipitation: A technique for identifying specific DNA sequences that are bound, in vivo, to proteins of interest. It involves formaldehyde fixation of CHROMATIN to crosslink the DNA-BINDING PROTEINS to the DNA. After shearing the DNA into small fragments, specific DNA-protein complexes are isolated by immunoprecipitation with protein-specific ANTIBODIES. Then, the DNA isolated from the complex can be identified by PCR amplification and sequencing.Plasmids: Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS.RNA Processing, Post-Transcriptional: Post-transcriptional biological modification of messenger, transfer, or ribosomal RNAs or their precursors. It includes cleavage, methylation, thiolation, isopentenylation, pseudouridine formation, conformational changes, and association with ribosomal protein.Sarcosine: An amino acid intermediate in the metabolism of choline.Protein Structure, Tertiary: The level of protein structure in which combinations of secondary protein structures (alpha helices, beta sheets, loop regions, and motifs) pack together to form folded shapes called domains. Disulfide bridges between cysteines in two different parts of the polypeptide chain along with other interactions between the chains play a role in the formation and stabilization of tertiary structure. Small proteins usually consist of only one domain but larger proteins may contain a number of domains connected by segments of polypeptide chain which lack regular secondary structure.Gene Expression Regulation, Fungal: Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action in fungi.Kinetics: The rate dynamics in chemical or physical systems.Nucleic Acid Conformation: The spatial arrangement of the atoms of a nucleic acid or polynucleotide that results in its characteristic 3-dimensional shape.Nuclear Proteins: Proteins found in the nucleus of a cell. Do not confuse with NUCLEOPROTEINS which are proteins conjugated with nucleic acids, that are not necessarily present in the nucleus.RNA Precursors: RNA transcripts of the DNA that are in some unfinished stage of post-transcriptional processing (RNA PROCESSING, POST-TRANSCRIPTIONAL) required for function. RNA precursors may undergo several steps of RNA SPLICING during which the phosphodiester bonds at exon-intron boundaries are cleaved and the introns are excised. Consequently a new bond is formed between the ends of the exons. Resulting mature RNAs can then be used; for example, mature mRNA (RNA, MESSENGER) is used as a template for protein production.Cell Line: Established cell cultures that have the potential to propagate indefinitely.Protein Subunits: Single chains of amino acids that are the units of multimeric PROTEINS. Multimeric proteins can be composed of identical or non-identical subunits. One or more monomeric subunits may compose a protomer which itself is a subunit structure of a larger assembly.Alpha-Amanitin: A cyclic octapeptide with a thioether bridge between the cystine and tryptophan. It inhibits RNA POLYMERASE II. Poisoning may require LIVER TRANSPLANTATION.Transcription Initiation, Genetic: The process that starts the transcription of an RNA molecule. It includes the assembly of the initiation complex and establishment of the start site.RNA, Bacterial: Ribonucleic acid in bacteria having regulatory and catalytic roles as well as involvement in protein synthesis.Transcription Initiation Site: The first nucleotide of a transcribed DNA sequence where RNA polymerase (DNA-DIRECTED RNA POLYMERASE) begins synthesizing the RNA transcript.Holoenzymes: Catalytically active enzymes that are formed by the combination of an apoenzyme (APOENZYMES) and its appropriate cofactors and prosthetic groups.Cloning, Molecular: The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.Fungal Proteins: Proteins found in any species of fungus.Phosphorylation: The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety.RNA Interference: A gene silencing phenomenon whereby specific dsRNAs (RNA, DOUBLE-STRANDED) trigger the degradation of homologous mRNA (RNA, MESSENGER). The specific dsRNAs are processed into SMALL INTERFERING RNA (siRNA) which serves as a guide for cleavage of the homologous mRNA in the RNA-INDUCED SILENCING COMPLEX. DNA METHYLATION may also be triggered during this process.Gene Expression Regulation: Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control (induction or repression) of gene action at the level of transcription or translation.Sigma Factor: A protein which is a subunit of RNA polymerase. It effects initiation of specific RNA chains from DNA.RNA Editing: A process that changes the nucleotide sequence of mRNA from that of the DNA template encoding it. Some major classes of RNA editing are as follows: 1, the conversion of cytosine to uracil in mRNA; 2, the addition of variable number of guanines at pre-determined sites; and 3, the addition and deletion of uracils, templated by guide-RNAs (RNA, GUIDE).Sequence Homology, Amino Acid: The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.Transcriptional Activation: Processes that stimulate the GENETIC TRANSCRIPTION of a gene or set of genes.Nucleosomes: The repeating structural units of chromatin, each consisting of approximately 200 base pairs of DNA wound around a protein core. This core is composed of the histones H2A, H2B, H3, and H4.RNA-Binding Proteins: Proteins that bind to RNA molecules. Included here are RIBONUCLEOPROTEINS and other proteins whose function is to bind specifically to RNA.RNA Caps: Nucleic acid structures found on the 5' end of eukaryotic cellular and viral messenger RNA and some heterogeneous nuclear RNAs. These structures, which are positively charged, protect the above specified RNAs at their termini against attack by phosphatases and other nucleases and promote mRNA function at the level of initiation of translation. Analogs of the RNA caps (RNA CAP ANALOGS), which lack the positive charge, inhibit the initiation of protein synthesis.Genes, Fungal: The functional hereditary units of FUNGI.Viral Proteins: Proteins found in any species of virus.DNA Polymerase I: A DNA-dependent DNA polymerase characterized in prokaryotes and may be present in higher organisms. It has both 3'-5' and 5'-3' exonuclease activity, but cannot use native double-stranded DNA as template-primer. It is not inhibited by sulfhydryl reagents and is active in both DNA synthesis and repair. EC 2.7.7.7.Transcription Termination, Genetic: The discontinuation of transcription at the end of a transcription unit, including the recognition of termination sites and release of the newly synthesized RNA molecule.Cyclin-Dependent Kinases: Protein kinases that control cell cycle progression in all eukaryotes and require physical association with CYCLINS to achieve full enzymatic activity. Cyclin-dependent kinases are regulated by phosphorylation and dephosphorylation events.DNA, Fungal: Deoxyribonucleic acid that makes up the genetic material of fungi.Transcription Factor TFIIA: An RNA POLYMERASE II specific transcription factor. It may play a role in transcriptional activation of gene expression by interacting with the TATA-BOX BINDING PROTEIN component of TRANSCRIPTION FACTOR TFIID.Recombinant Proteins: Proteins prepared by recombinant DNA technology.Models, Molecular: Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.Models, Genetic: Theoretical representations that simulate the behavior or activity of genetic processes or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.Bacteriophage T7: Virulent bacteriophage and type species of the genus T7-like phages, in the family PODOVIRIDAE, that infects E. coli. It consists of linear double-stranded DNA, terminally redundant, and non-permuted.Potassium Permanganate: Permanganic acid (HMnO4), potassium salt. A highly oxidative, water-soluble compound with purple crystals, and a sweet taste. (From McGraw-Hill Dictionary of Scientific and Technical Information, 4th ed)DNA Polymerase III: A DNA-dependent DNA polymerase characterized in E. coli and other lower organisms but may be present in higher organisms. Use also for a more complex form of DNA polymerase III designated as DNA polymerase III* or pol III* which is 15 times more active biologically than DNA polymerase I in the synthesis of DNA. This polymerase has both 3'-5' and 5'-3' exonuclease activities, is inhibited by sulfhydryl reagents, and has the same template-primer dependence as pol II. EC 2.7.7.7.DNA, Viral: Deoxyribonucleic acid that makes up the genetic material of viruses.mRNA Cleavage and Polyadenylation Factors: Factors that are involved in directing the cleavage and POLYADENYLATION of the of MESSENGER RNA near the site of the RNA 3' POLYADENYLATION SIGNALS.RNA Viruses: Viruses whose genetic material is RNA.DNA Primers: Short sequences (generally about 10 base pairs) of DNA that are complementary to sequences of messenger RNA and allow reverse transcriptases to start copying the adjacent sequences of mRNA. Primers are used extensively in genetic and molecular biology techniques.Trans-Activators: Diffusible gene products that act on homologous or heterologous molecules of viral or cellular DNA to regulate the expression of proteins.RNA, Double-Stranded: RNA consisting of two strands as opposed to the more prevalent single-stranded RNA. Most of the double-stranded segments are formed from transcription of DNA by intramolecular base-pairing of inverted complementary sequences separated by a single-stranded loop. Some double-stranded segments of RNA are normal in all organisms.Recombinant Fusion Proteins: Recombinant proteins produced by the GENETIC TRANSLATION of fused genes formed by the combination of NUCLEIC ACID REGULATORY SEQUENCES of one or more genes with the protein coding sequences of one or more genes.DNA Helicases: Proteins that catalyze the unwinding of duplex DNA during replication by binding cooperatively to single-stranded regions of DNA or to short regions of duplex DNA that are undergoing transient opening. In addition DNA helicases are DNA-dependent ATPases that harness the free energy of ATP hydrolysis to translocate DNA strands.Precipitin Tests: Serologic tests in which a positive reaction manifested by visible CHEMICAL PRECIPITATION occurs when a soluble ANTIGEN reacts with its precipitins, i.e., ANTIBODIES that can form a precipitate.Cell-Free System: A fractionated cell extract that maintains a biological function. A subcellular fraction isolated by ultracentrifugation or other separation techniques must first be isolated so that a process can be studied free from all of the complex side reactions that occur in a cell. The cell-free system is therefore widely used in cell biology. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p166)RNA 3' End Processing: The steps that generate the 3' ends of mature RNA molecules. For most mRNAs (RNA, MESSENGER), 3' end processing referred to as POLYADENYLATION includes the addition of POLY A.Cyclin T: A cyclin subtype that is found associated with CYCLIN-DEPENDENT KINASE 9. Unlike traditional cyclins, which regulate the CELL CYCLE, type T cyclins appear to regulate transcription and are components of positive transcriptional elongation factor B.RNA, Transfer: The small RNA molecules, 73-80 nucleotides long, that function during translation (TRANSLATION, GENETIC) to align AMINO ACIDS at the RIBOSOMES in a sequence determined by the mRNA (RNA, MESSENGER). There are about 30 different transfer RNAs. Each recognizes a specific CODON set on the mRNA through its own ANTICODON and as aminoacyl tRNAs (RNA, TRANSFER, AMINO ACYL), each carries a specific amino acid to the ribosome to add to the elongating peptide chains.RNA Polymerase Sigma 54: A DNA-directed RNA polymerase found in BACTERIA. It is a holoenzyme that consists of multiple subunits including sigma factor 54.Ribonucleoproteins: Complexes of RNA-binding proteins with ribonucleic acids (RNA).Peptide Chain Elongation, Translational: A process of GENETIC TRANSLATION, when an amino acid is transferred from its cognate TRANSFER RNA to the lengthening chain of PEPTIDES.Molecular Weight: The sum of the weight of all the atoms in a molecule.RNA Stability: The extent to which an RNA molecule retains its structural integrity and resists degradation by RNASE, and base-catalyzed HYDROLYSIS, under changing in vivo or in vitro conditions.Nucleic Acid Hybridization: Widely used technique which exploits the ability of complementary sequences in single-stranded DNAs or RNAs to pair with each other to form a double helix. Hybridization can take place between two complimentary DNA sequences, between a single-stranded DNA and a complementary RNA, or between two RNA sequences. The technique is used to detect and isolate specific sequences, measure homology, or define other characteristics of one or both strands. (Kendrew, Encyclopedia of Molecular Biology, 1994, p503)Peptide Elongation Factors: Protein factors uniquely required during the elongation phase of protein synthesis.Methylation: Addition of methyl groups. In histo-chemistry methylation is used to esterify carboxyl groups and remove sulfate groups by treating tissue sections with hot methanol in the presence of hydrochloric acid. (From Stedman, 25th ed)Genes: A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms.Pol1 Transcription Initiation Complex Proteins: Factors that form a preinitiation complex at promoters that are specifically transcribed by RNA POLYMERASE I.RNA, Untranslated: RNA which does not code for protein but has some enzymatic, structural or regulatory function. Although ribosomal RNA (RNA, RIBOSOMAL) and transfer RNA (RNA, TRANSFER) are also untranslated RNAs they are not included in this scope.Nucleotides: The monomeric units from which DNA or RNA polymers are constructed. They consist of a purine or pyrimidine base, a pentose sugar, and a phosphate group. (From King & Stansfield, A Dictionary of Genetics, 4th ed)Electrophoresis, Polyacrylamide Gel: Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.Chromatin Assembly and Disassembly: The mechanisms effecting establishment, maintenance, and modification of that specific physical conformation of CHROMATIN determining the transcriptional accessibility or inaccessibility of the DNA.Conserved Sequence: A sequence of amino acids in a polypeptide or of nucleotides in DNA or RNA that is similar across multiple species. A known set of conserved sequences is represented by a CONSENSUS SEQUENCE. AMINO ACID MOTIFS are often composed of conserved sequences.RNA Helicases: A family of proteins that promote unwinding of RNA during splicing and translation.Nucleic Acid Synthesis Inhibitors: Compounds that inhibit cell production of DNA or RNA.Repressor Proteins: Proteins which maintain the transcriptional quiescence of specific GENES or OPERONS. Classical repressor proteins are DNA-binding proteins that are normally bound to the OPERATOR REGION of an operon, or the ENHANCER SEQUENCES of a gene until a signal occurs that causes their release.RNA, Antisense: RNA molecules which hybridize to complementary sequences in either RNA or DNA altering the function of the latter. Endogenous antisense RNAs function as regulators of gene expression by a variety of mechanisms. Synthetic antisense RNAs are used to effect the functioning of specific genes for investigative or therapeutic purposes.Operon: In bacteria, a group of metabolically related genes, with a common promoter, whose transcription into a single polycistronic MESSENGER RNA is under the control of an OPERATOR REGION.Temperature: The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.Cell Nucleolus: Within most types of eukaryotic CELL NUCLEUS, a distinct region, not delimited by a membrane, in which some species of rRNA (RNA, RIBOSOMAL) are synthesized and assembled into ribonucleoprotein subunits of ribosomes. In the nucleolus rRNA is transcribed from a nucleolar organizer, i.e., a group of tandemly repeated chromosomal genes which encode rRNA and which are transcribed by RNA polymerase I. (Singleton & Sainsbury, Dictionary of Microbiology & Molecular Biology, 2d ed)Gene Expression Regulation, Viral: Any of the processes by which cytoplasmic factors influence the differential control of gene action in viruses.Restriction Mapping: Use of restriction endonucleases to analyze and generate a physical map of genomes, genes, or other segments of DNA.Virus Replication: The process of intracellular viral multiplication, consisting of the synthesis of PROTEINS; NUCLEIC ACIDS; and sometimes LIPIDS, and their assembly into a new infectious particle.Polyadenylation: The addition of a tail of polyadenylic acid (POLY A) to the 3' end of mRNA (RNA, MESSENGER). Polyadenylation involves recognizing the processing site signal, (AAUAAA), and cleaving of the mRNA to create a 3' OH terminal end to which poly A polymerase (POLYNUCLEOTIDE ADENYLYLTRANSFERASE) adds 60-200 adenylate residues. The 3' end processing of some messenger RNAs, such as histone mRNA, is carried out by a different process that does not include the addition of poly A as described here.DNA, Ribosomal: DNA sequences encoding RIBOSOMAL RNA and the segments of DNA separating the individual ribosomal RNA genes, referred to as RIBOSOMAL SPACER DNA.Acetylation: Formation of an acetyl derivative. (Stedman, 25th ed)Chromosomal Proteins, Non-Histone: Nucleoproteins, which in contrast to HISTONES, are acid insoluble. They are involved in chromosomal functions; e.g. they bind selectively to DNA, stimulate transcription resulting in tissue-specific RNA synthesis and undergo specific changes in response to various hormones or phytomitogens.Sequence Alignment: The arrangement of two or more amino acid or base sequences from an organism or organisms in such a way as to align areas of the sequences sharing common properties. The degree of relatedness or homology between the sequences is predicted computationally or statistically based on weights assigned to the elements aligned between the sequences. This in turn can serve as a potential indicator of the genetic relatedness between the organisms.tat Gene Products, Human Immunodeficiency Virus: Proteins encoded by the TAT GENES of the HUMAN IMMUNODEFICIENCY VIRUS.Drosophila: A genus of small, two-winged flies containing approximately 900 described species. These organisms are the most extensively studied of all genera from the standpoint of genetics and cytology.Reverse Transcriptase Polymerase Chain Reaction: A variation of the PCR technique in which cDNA is made from RNA via reverse transcription. The resultant cDNA is then amplified using standard PCR protocols.Sequence Deletion: Deletion of sequences of nucleic acids from the genetic material of an individual.Uridine Triphosphate: Uridine 5'-(tetrahydrogen triphosphate). A uracil nucleotide containing three phosphate groups esterified to the sugar moiety.Bacterial Proteins: Proteins found in any species of bacterium.Models, Biological: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.Drosophila melanogaster: A species of fruit fly much used in genetics because of the large size of its chromosomes.Histone Acetyltransferases: Enzymes that catalyze acyl group transfer from ACETYL-CoA to HISTONES forming CoA and acetyl-histones.Serine: A non-essential amino acid occurring in natural form as the L-isomer. It is synthesized from GLYCINE or THREONINE. It is involved in the biosynthesis of PURINES; PYRIMIDINES; and other amino acids.Gene Products, tat: Trans-acting transcription factors produced by retroviruses such as HIV. They are nuclear proteins whose expression is required for viral replication. The tat protein stimulates LONG TERMINAL REPEAT-driven RNA synthesis for both viral regulatory and viral structural proteins. tat stands for trans-activation of transcription.Schizosaccharomyces: A genus of ascomycetous fungi of the family Schizosaccharomycetaceae, order Schizosaccharomycetales.Poly A: A group of adenine ribonucleotides in which the phosphate residues of each adenine ribonucleotide act as bridges in forming diester linkages between the ribose moieties.RNA, Spliced Leader: The small RNAs which provide spliced leader sequences, SL1, SL2, SL3, SL4 and SL5 (short sequences which are joined to the 5' ends of pre-mRNAs by TRANS-SPLICING). They are found primarily in primitive eukaryotes (protozoans and nematodes).Mutagenesis: Process of generating a genetic MUTATION. It may occur spontaneously or be induced by MUTAGENS.DNA Replication: The process by which a DNA molecule is duplicated.DNA Footprinting: A method for determining the sequence specificity of DNA-binding proteins. DNA footprinting utilizes a DNA damaging agent (either a chemical reagent or a nuclease) which cleaves DNA at every base pair. DNA cleavage is inhibited where the ligand binds to DNA. (from Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)DNA, Bacterial: Deoxyribonucleic acid that makes up the genetic material of bacteria.Protein Conformation: The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).Oligoribonucleotides: A group of ribonucleotides (up to 12) in which the phosphate residues of each ribonucleotide act as bridges in forming diester linkages between the ribose moieties.T-Phages: A series of 7 virulent phages which infect E. coli. The T-even phages T2, T4; (BACTERIOPHAGE T4), and T6, and the phage T5 are called "autonomously virulent" because they cause cessation of all bacterial metabolism on infection. Phages T1, T3; (BACTERIOPHAGE T3), and T7; (BACTERIOPHAGE T7) are called "dependent virulent" because they depend on continued bacterial metabolism during the lytic cycle. The T-even phages contain 5-hydroxymethylcytosine in place of ordinary cytosine in their DNA.Transcription Factor TFIIIB: One of several general transcription factors that are specific for RNA POLYMERASE III. TFIIIB recruits and positions pol III over the initiation site and remains stably bound to the DNA through multiple rounds of re-initiation by RNA POLYMERASE III.Substrate Specificity: A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.RNA, Catalytic: RNA that has catalytic activity. The catalytic RNA sequence folds to form a complex surface that can function as an enzyme in reactions with itself and other molecules. It may function even in the absence of protein. There are numerous examples of RNA species that are acted upon by catalytic RNA, however the scope of this enzyme class is not limited to a particular type of substrate.Cyclin C: A cyclin subtype that binds to the CYCLIN-DEPENDENT KINASE 3 and CYCLIN-DEPENDENT KINASE 8. Cyclin C plays a dual role as a transcriptional regulator and a G1 phase CELL CYCLE regulator.Suppression, Genetic: Mutation process that restores the wild-type PHENOTYPE in an organism possessing a mutationally altered GENOTYPE. The second "suppressor" mutation may be on a different gene, on the same gene but located at a distance from the site of the primary mutation, or in extrachromosomal genes (EXTRACHROMOSOMAL INHERITANCE).Sequence Homology, Nucleic Acid: The sequential correspondence of nucleotides in one nucleic acid molecule with those of another nucleic acid molecule. Sequence homology is an indication of the genetic relatedness of different organisms and gene function.Transfection: The uptake of naked or purified DNA by CELLS, usually meaning the process as it occurs in eukaryotic cells. It is analogous to bacterial transformation (TRANSFORMATION, BACTERIAL) and both are routinely employed in GENE TRANSFER TECHNIQUES.UracilCyclin H: A cyclin subtype that is found as a component of a heterotrimeric complex containing cyclin-dependent kinase 7 and CDK-activating kinase assembly factor. The complex plays a role in cellular proliferation by phosphorylating several CYCLIN DEPENDENT KINASES at specific regulatory threonine sites.Gene Silencing: Interruption or suppression of the expression of a gene at transcriptional or translational levels.Nucleotidyltransferases: A class of enzymes that transfers nucleotidyl residues. EC 2.7.7.RNA Nucleotidyltransferases: Enzymes that catalyze the template-directed incorporation of ribonucleotides into an RNA chain. EC 2.7.7.-.DNA Polymerase beta: A DNA repair enzyme that catalyzes DNA synthesis during base excision DNA repair. EC 2.7.7.7.Protein Kinases: A family of enzymes that catalyze the conversion of ATP and a protein to ADP and a phosphoprotein.DNA Repair: The reconstruction of a continuous two-stranded DNA molecule without mismatch from a molecule which contained damaged regions. The major repair mechanisms are excision repair, in which defective regions in one strand are excised and resynthesized using the complementary base pairing information in the intact strand; photoreactivation repair, in which the lethal and mutagenic effects of ultraviolet light are eliminated; and post-replication repair, in which the primary lesions are not repaired, but the gaps in one daughter duplex are filled in by incorporation of portions of the other (undamaged) daughter duplex. Excision repair and post-replication repair are sometimes referred to as "dark repair" because they do not require light.Gene Deletion: A genetic rearrangement through loss of segments of DNA or RNA, bringing sequences which are normally separated into close proximity. This deletion may be detected using cytogenetic techniques and can also be inferred from the phenotype, indicating a deletion at one specific locus.Transcription Factors, TFIII: Factors that bind to RNA POLYMERASE III and aid in transcription. They include the assembly factors TFIIIA and TFIIIC and the initiation factor TFIIIB. All combine to form a preinitiation complex at the promotor that directs the binding of RNA POLYMERASE III.Sequence Analysis, DNA: A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.Open Reading Frames: A sequence of successive nucleotide triplets that are read as CODONS specifying AMINO ACIDS and begin with an INITIATOR CODON and end with a stop codon (CODON, TERMINATOR).Yeasts: A general term for single-celled rounded fungi that reproduce by budding. Brewers' and bakers' yeasts are SACCHAROMYCES CEREVISIAE; therapeutic dried yeast is YEAST, DRIED.Protein Biosynthesis: The biosynthesis of PEPTIDES and PROTEINS on RIBOSOMES, directed by MESSENGER RNA, via TRANSFER RNA that is charged with standard proteinogenic AMINO ACIDS.Cell Extracts: Preparations of cell constituents or subcellular materials, isolates, or substances.Multiprotein Complexes: Macromolecular complexes formed from the association of defined protein subunits.RNA, Heterogeneous Nuclear: Nuclear nonribosomal RNA larger than about 1000 nucleotides, the mass of which is rapidly synthesized and degraded within the cell nucleus. Some heterogeneous nuclear RNA may be a precursor to mRNA. However, the great bulk of total hnRNA hybridizes with nuclear DNA rather than with mRNA.3' Flanking Region: The region of DNA which borders the 3' end of a transcription unit and where a variety of regulatory sequences are located.Drosophila Proteins: Proteins that originate from insect species belonging to the genus DROSOPHILA. The proteins from the most intensely studied species of Drosophila, DROSOPHILA MELANOGASTER, are the subject of much interest in the area of MORPHOGENESIS and development.Ribonucleotides: Nucleotides in which the purine or pyrimidine base is combined with ribose. (Dorland, 28th ed)Lysine: An essential amino acid. It is often added to animal feed.Mutagenesis, Site-Directed: Genetically engineered MUTAGENESIS at a specific site in the DNA molecule that introduces a base substitution, or an insertion or deletion.Genes, Viral: The functional hereditary units of VIRUSES.Repetitive Sequences, Amino Acid: A sequential pattern of amino acids occurring more than once in the same protein sequence.Structure-Activity Relationship: The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.RNA Cleavage: A reaction that severs one of the sugar-phosphate linkages of the phosphodiester backbone of RNA. It is catalyzed enzymatically, chemically, or by radiation. Cleavage may be exonucleolytic, or endonucleolytic.Ultraviolet Rays: That portion of the electromagnetic spectrum immediately below the visible range and extending into the x-ray frequencies. The longer wavelengths (near-UV or biotic or vital rays) are necessary for the endogenous synthesis of vitamin D and are also called antirachitic rays; the shorter, ionizing wavelengths (far-UV or abiotic or extravital rays) are viricidal, bactericidal, mutagenic, and carcinogenic and are used as disinfectants.Oligonucleotides: Polymers made up of a few (2-20) nucleotides. In molecular genetics, they refer to a short sequence synthesized to match a region where a mutation is known to occur, and then used as a probe (OLIGONUCLEOTIDE PROBES). (Dorland, 28th ed)Regulatory Sequences, Nucleic Acid: Nucleic acid sequences involved in regulating the expression of genes.Ribonucleoproteins, Small Nuclear: Highly conserved nuclear RNA-protein complexes that function in RNA processing in the nucleus, including pre-mRNA splicing and pre-mRNA 3'-end processing in the nucleoplasm, and pre-rRNA processing in the nucleolus (see RIBONUCLEOPROTEINS, SMALL NUCLEOLAR).Gene Expression Regulation, Bacterial: Any of the processes by which cytoplasmic or intercellular factors influence the differential control of gene action in bacteria.RNA, Protozoan: Ribonucleic acid in protozoa having regulatory and catalytic roles as well as involvement in protein synthesis.RNA, Plant: Ribonucleic acid in plants having regulatory and catalytic roles as well as involvement in protein synthesis.Globins: A superfamily of proteins containing the globin fold which is composed of 6-8 alpha helices arranged in a characterstic HEME enclosing structure.Ribonucleases: Enzymes that catalyze the hydrolysis of ester bonds within RNA. EC 3.1.-.