Poly U
Uracil Nucleotides
Polynucleotides
Poly A
Poly(ADP-ribose) Polymerases
Poly C
Poly I-C
Ribosomes
Poly dA-dT
Poly(A)-Binding Proteins
Poly Adenosine Diphosphate Ribose
Poly G
Poly I
Poly T
Polydeoxyribonucleotides
Polyribonucleotides
Poly(A)-Binding Protein I
Ribonucleoprotein, U1 Small Nuclear
Action of partially thiolated polynucleotides on the DNA polymerase alpha from regenerating rat liver. (1/527)
The effects of partially thiolated polynucleotides on the DNA polymerase alpha from regenerating rat liver were investigated. The enzyme was isolated from the nuclear fraction essentially according to the method of Baril et al.; it was characterized as the alpha polymerase on the basis of its response to synthetic templates and its inhibition with N-ethylmaleimide. Although polycytidylic acid had no effect on the DNA polymerase alpha either as a template or as an inhibitor, partially thiolated polycytidylic acid (MPC) was found to be a potent inhibitor, its activity being directly related to its extent of thiolation (percentage of 5-mercaptocytidylate units in the polymer). In comparison, the DNA polymerase beta which was purified from normal rat liver nuclear fraction, was much less sensitive to inhibition by MPC. Analysis of the inhibition of the alpha polymerase by the method of Lineweaver and Burk showed that the inhibitory action of MPC was competitively reversible with the DNA template, but the binding of the 7.2%-thiolated MPC to the enzyme was much stronger than that of the template (Ki/Km less than 0.03). Polyuridylic acid as such showed some inhibitory activity which increased on partial thiolation, but the 8.4%-thiolated polyuridylic acid was less active than the 7.2% MPC. When MPC was annealed with polyinosinic acid, it lost 80% of its inhibitory activity in the double-stranded configuration. However, 1 to 2%-thiolated DNA isolates were significantly more potent inhibitors than were comparable (1.2%-thiolated) MPC and showed competitive reversibility with the unmodified (but "activated") DNA template. These results indicate that the inhibitory activities of partially thiolated polynucleotides depend not only on the percentage of 5-mercapto groups but also on the configuration, base composition, and other specific structural properties. (+info)The nucleoporin nup153 plays a critical role in multiple types of nuclear export. (2/527)
The fundamental process of nucleocytoplasmic transport takes place through the nuclear pore. Peripheral pore structures are presumably poised to interact with transport receptors and their cargo as these receptor complexes first encounter the pore. One such peripheral structure likely to play an important role in nuclear export is the basket structure located on the nuclear side of the pore. At present, Nup153 is the only nucleoporin known to localize to the surface of this basket, suggesting that Nup153 is potentially one of the first pore components an RNA or protein encounters during export. In this study, anti-Nup153 antibodies were used to probe the role of Nup153 in nuclear export in Xenopus oocytes. We found that Nup153 antibodies block three major classes of RNA export, that of snRNA, mRNA, and 5S rRNA. Nup153 antibodies also block the NES protein export pathway, specifically the export of the HIV Rev protein, as well as Rev-dependent RNA export. Not all export was blocked; Nup153 antibodies did not impede the export of tRNA or the recycling of importin beta to the cytoplasm. The specific antibodies used here also did not affect nuclear import, whether mediated by importin alpha/beta or by transportin. Overall, the results indicate that Nup153 is crucial to multiple classes of RNA and protein export, being involved at a vital juncture point in their export pathways. This juncture point appears to be one that is bypassed by tRNA during its export. We asked whether a physical interaction between RNA and Nup153 could be observed, using homoribopolymers as sequence-independent probes for interaction. Nup153, unlike four other nucleoporins including Nup98, associated strongly with poly(G) and significantly with poly(U). Thus, Nup153 is unique among the nucleoporins tested in its ability to interact with RNA and must do so either directly or indirectly through an adaptor protein. These results suggest a unique mechanistic role for Nup153 in the export of multiple cargos. (+info)Effect of buffer conditions on the position of tRNA on the 70 S ribosome as visualized by cryoelectron microscopy. (3/527)
The effect of buffer conditions on the binding position of tRNA on the Escherichia coli 70 S ribosome have been studied by means of three-dimensional (3D) cryoelectron microscopy. Either deacylated tRNAfMet or fMet-tRNAfMet were bound to the 70 S ribosomes, which were programmed with a 46-nucleotide mRNA having AUG codon in the middle, under two different buffer conditions (conventional buffer: containing Tris and higher Mg2+ concentration [10-15 mM]; and polyamine buffer: containing Hepes, lower Mg2+ concentration [6 mM], and polyamines). Difference maps, obtained by subtracting 3D maps of naked control ribosome in the corresponding buffer from the 3D maps of tRNA.ribosome complexes, reveal the distinct locations of tRNA on the ribosome. The position of deacylated tRNAfMet depends on the buffer condition used, whereas that of fMet-tRNAfMet remains the same in both buffer conditions. The acylated tRNA binds in the classical P site, whereas deacylated tRNA binds mostly in an intermediate P/E position under the conventional buffer condition and mostly in the position corresponding to the classical P site, i. e. in the P/P state, under the polyamine buffer conditions. (+info)Cellular proteins bind to the poly(U) tract of the 3' untranslated region of hepatitis C virus RNA genome. (4/527)
UV cross-linking analyses were performed in an attempt to determine cellular protein-viral RNA interactions with the 3' untranslated region (3' UTR) of the hepatitis C virus RNA genome. Two cellular proteins, with estimated molecular masses of 58 kDa (p58) and 35 kDa (p35), respectively, were found to specifically bind to the 3' UTR. The p58 protein was determined to be the polypyrimidine tract-binding protein. In addition to binding to the conserved 98 nucleotides (nt) of the 3' UTR, p58 also binds to the poly(U) tract of the 3' UTR. The p35 protein was found to interact only with the poly(U) tract of the 3' UTR. These conclusions are supported by the following findings: (1) p58, and not p35, binds to the 3' end conserved 98 nt, (2) both p58 and p35 bind to a 3' UTR RNA with a deletion of the conserved 98 nt, (3) the 98-nt deletion mutant 3' UTR competed out both p58 and p35 binding, (4) a poly(U) homopolymer competed out both p58 and p35 binding, (5) a 3' UTR RNA with deletion of the poly(U) tract competed out only p58 binding but not p35 binding, and (6) an RNA containing the variable region of the 3' UTR with a deletion of both poly(U) tract and 98 nt failed to compete for binding of either p58 or p35. Interaction of these cellular proteins with the HCV 3' UTR is probably involved in regulation of translation and/or replication of the HCV RNA genome. (+info)Regeneration of renal proximal tubules after mercuric chloride injury is accompanied by increased binding of aminoacyl-transfer ribonucleic acid. (5/527)
Homogenates of rat kidney cortex obtained 1,3 or 14 days after a single injection of HgCl2 were used to prepare the post-microsomal pH5 supernatant fraction. The activity of this fraction for peptide synthesis from [14C]phenylalanyl-tRNA was significantly increased at 1 and 3 days, at which time the proximal tubules are regenerating [Cuppage & Tate (1967) Am. J. Pathol. 51, 405-429]. This increased activity could not be attributed to a decreased inhibitory activity, but was due to an increased aminoacyl-tRNA binding, i.e. elongation-factor-1 activity, in the supernatant fraction. (+info)Chemical shift perturbation studies of the interactions of the second RNA-binding domain of the Drosophila sex-lethal protein with the transformer pre-mRNA polyuridine tract and 3' splice-site sequences. (6/527)
The interactions of the second RNA-binding domain of the Drosophila melanogaster Sex-lethal protein (Sxl RBD2) with the oligoribonucleotides, GUUUUUUUU (GU8) and CUAGUG, representing the sequences surrounding an alternative 3'-splicing site of the transformer pre-mRNA (GU8CUAGUG), were studied using heteronuclear two-dimensional NMR techniques. The 1H and 15N chemical shifts of the backbone amide resonances upon titration of Sxl RBD2 with each of these RNAs were recorded. It was found that Sxl RBD2 can bind not only to the polyuridine tract, GU8, but also to the downstream 3' splice-site sequence, CUAGUG, with similar affinities. In contrast, a nonspecific sequence, C8, did not bind to Sxl RBD2. This result is consistent with previous in vitro RNA-selection and UV-cross-linking results which indicated that the Sex-lethal protein binds to the uridine stretch and the AG dinucleotide in the consensus sequence, AUnNnAGU. In both cases, the chemical-shift perturbations were significant for almost the same amino acid residues, including the two central beta-strands formed by the RNP2-motif and RNP1-motif with the two highly conserved aromatic residues (Y214 and F256) in the middle. As the first RNA-binding domain of Sex-lethal (Sxl RBD1) has a characteristic aliphatic residue at one of the two corresponding positions (I128 and F170), Y214 of Sxl RBD2 was replaced by Ile using site-directed mutagenesis. On the one hand, the 1H and 15N chemical-shift perturbations indicated that GU8 binds to the same interface of mutant Sxl RBD2 as of wild-type Sxl RBD2, although its binding affinity was decreased significantly. On the other hand, the specific binding of Sxl RBD2 to CUAGUG was abolished almost completely by the Y-->I mutation. Taken together, the present results indicate that the interface residues that bind with GU8 and CUAGUG are much the same, but the role of the Y214 residue is clearly different between these two target sequences. (+info)Ribosomal subunits from Tetrahymena pyriformis. Isolation and properties of active 40-S and 60-S subunits. (7/527)
Tetrahymena pyriformis ribosomal subunits were obtained by incubation of post-mitochondrial supernatant in the presence of 0.2 mM GTP and 0.1 mM puromycin for 45 min at 28 degrees C, followed by sucrose density gradient centrifugation. Isolated 40-S subunits were able to reassociate in vitro in the presence of 5 mM MgCl2 and 50 mM KCl and to perform poly(U)-dependent protein synthesis. The 60-S subunit carries the peptidyl transferase activity. The number of proteins in T. pyriformis ribosomal subunits was determined by two-dimensional polyacrylamide gel electrophoresis. The 40-S subunit contains 30 different protein species (including two acidic proteins). The 60-S subunit contains 35 different protein species (including two acidic proteins). The proteins were numbered following the system of Kaltschmidt and Wittmann. (+info)Isolation of a mammalian homologue of a fission yeast differentiation regulator. (8/527)
In the fission yeast Schizosaccharomyces pombe the nrd1(+) gene encoding an RNA binding protein negatively regulates the onset of differentiation. Its biological role is to block differentiation by repressing a subset of the Ste11-regulated genes essential for conjugation and meiosis until the cells reach a critical level of nutrient starvation. By using the phenotypic suppression of the S. pombe temperature-sensitive pat1 mutant that commits lethal haploid meiosis at the restrictive temperature, we have cloned ROD1, a functional homologue of nrd1(+), from rat and human cDNA libraries. Like nrd1(+), ROD1 encodes a protein with four repeats of typical RNA binding domains, though its amino acid homology to Nrd1 is limited. When expressed in the fission yeast, ROD1 behaves in a way that is functionally similar to nrd1(+), being able to repress Ste11-regulated genes and to inhibit conjugation upon overexpression. ROD1 is predominantly expressed in hematopoietic cells or organs of adult and embryonic rat. Like nrd1(+) for fission yeast differentiation, overexpressed ROD1 effectively blocks both 12-O-tetradecanoyl phorbol-13-acetate-induced megakaryocytic and sodium butyrate-induced erythroid differentiation of the K562 human leukemia cells without affecting their proliferative ability. These results suggest a role for ROD1 in differentiation control in mammalian cells. We discuss the possibility that a differentiation control system found in the fission yeast might well be conserved in more complex organisms, including mammals. (+info)I'm sorry for any confusion, but "Poly U" is not a recognized medical term or abbreviation in the English language. It could potentially refer to Polytechnic University or Hong Kong Polytechnic University, but it does not have a specific medical connotation. If you have more context or information, I'd be happy to help further!
"Poly A-U" is not a standard medical term. However, in biochemistry and genetics, "poly A" and "poly U" refer to repeating sequences of adenine (A) or uracil (U) nucleotides in DNA or RNA molecules, respectively.
"Poly A" is a post-transcriptional modification that occurs in mRNA, where multiple adenine nucleotides are added to the 3' end of the transcript. This process is important for the stability and translation of mRNA in eukaryotic cells.
"Poly U," on the other hand, can be found in some RNA molecules such as in the 3' untranslated region (UTR) of certain mRNAs or in specific types of non-coding RNAs like U-rich small nuclear RNAs (snRNAs).
Therefore, "Poly A-U" may refer to alternating sequences of adenine and uracil nucleotides in a DNA or RNA molecule. However, it is essential to consider the context in which this term is used to provide an accurate interpretation.
Uracil nucleotides are chemical compounds that play a crucial role in the synthesis, repair, and replication of DNA and RNA. Specifically, uracil nucleotides refer to the group of molecules that contain the nitrogenous base uracil, which is linked to a ribose sugar through a beta-glycosidic bond. This forms the nucleoside uridine, which can then be phosphorylated to create the uracil nucleotide.
Uracil nucleotides are important in the formation of RNA, where uracil base pairs with adenine through two hydrogen bonds during transcription. However, uracil is not typically found in DNA, and its presence in DNA can indicate damage or mutation. When uracil is found in DNA, it is usually the result of a process called deamination, where the nitrogenous base cytosine is spontaneously converted to uracil. This can lead to errors during replication, as uracil will pair with adenine instead of guanine, leading to a C-to-T or G-to-A mutation.
To prevent this type of mutation, cells have enzymes called uracil DNA glycosylases that recognize and remove uracil from DNA. This initiates the base excision repair pathway, which removes the damaged nucleotide and replaces it with a correct one. Overall, uracil nucleotides are essential for proper cellular function, but their misincorporation into DNA can have serious consequences for genome stability.
Polynucleotides are long, chain-like molecules composed of repeating units called nucleotides. Each nucleotide contains a sugar molecule (deoxyribose in DNA or ribose in RNA), a phosphate group, and a nitrogenous base (adenine, guanine, cytosine, thymine in DNA or adenine, guanine, uracil, cytosine in RNA). In DNA, the nucleotides are joined together by phosphodiester bonds between the sugar of one nucleotide and the phosphate group of the next, creating a double helix structure. In RNA, the nucleotides are also joined by phosphodiester bonds but form a single strand. Polynucleotides play crucial roles in storing and transmitting genetic information within cells.
"Poly A" is an abbreviation for "poly(A) tail" or "polyadenylation." It refers to the addition of multiple adenine (A) nucleotides to the 3' end of eukaryotic mRNA molecules during the process of transcription. This poly(A) tail plays a crucial role in various aspects of mRNA metabolism, including stability, transport, and translation. The length of the poly(A) tail can vary from around 50 to 250 nucleotides depending on the cell type and developmental stage.
Ribonucleases (RNases) are a group of enzymes that catalyze the degradation of ribonucleic acid (RNA) molecules by hydrolyzing the phosphodiester bonds. These enzymes play crucial roles in various biological processes, such as RNA processing, turnover, and quality control. They can be classified into several types based on their specificities, mechanisms, and cellular localizations.
Some common classes of ribonucleases include:
1. Endoribonucleases: These enzymes cleave RNA internally, at specific sequences or structural motifs. Examples include RNase A, which targets single-stranded RNA; RNase III, which cuts double-stranded RNA at specific stem-loop structures; and RNase T1, which recognizes and cuts unpaired guanosine residues in RNA molecules.
2. Exoribonucleases: These enzymes remove nucleotides from the ends of RNA molecules. They can be further divided into 5'-3' exoribonucleases, which degrade RNA starting from the 5' end, and 3'-5' exoribonucleases, which start at the 3' end. Examples include Xrn1, a 5'-3' exoribonuclease involved in mRNA decay; and Dis3/RRP6, a 3'-5' exoribonuclease that participates in ribosomal RNA processing and degradation.
3. Specific ribonucleases: These enzymes target specific RNA molecules or regions with high precision. For example, RNase P is responsible for cleaving the 5' leader sequence of precursor tRNAs (pre-tRNAs) during their maturation; and RNase MRP is involved in the processing of ribosomal RNA and mitochondrial RNA molecules.
Dysregulation or mutations in ribonucleases have been implicated in various human diseases, such as neurological disorders, cancer, and viral infections. Therefore, understanding their functions and mechanisms is crucial for developing novel therapeutic strategies.
I'm sorry for any confusion, but "Poly C" is not a widely recognized medical term or abbreviation in the field of medicine or biology. It might be a typographical error or a shorthand notation used in a specific context. If you could provide more context or clarify what you mean by "Poly C," I would be happy to help further.
Poly(I):C is a synthetic double-stranded RNA (dsRNA) molecule made up of polycytidylic acid (poly C) and polyinosinic acid (poly I), joined by a 1:1 ratio of their phosphodiester linkages. It is used in research as an immunostimulant, particularly to induce the production of interferons and other cytokines, and to activate immune cells such as natural killer (NK) cells, dendritic cells, and macrophages. Poly(I):C has been studied for its potential use in cancer immunotherapy and as a vaccine adjuvant. It can also induce innate antiviral responses and has been explored as an antiviral agent itself.
Ribosomes are complex macromolecular structures composed of ribonucleic acid (RNA) and proteins that play a crucial role in protein synthesis within cells. They serve as the site for translation, where messenger RNA (mRNA) is translated into a specific sequence of amino acids to create a polypeptide chain, which eventually folds into a functional protein.
Ribosomes consist of two subunits: a smaller subunit and a larger subunit. These subunits are composed of ribosomal RNA (rRNA) molecules and proteins. In eukaryotic cells, the smaller subunit is denoted as the 40S subunit, while the larger subunit is referred to as the 60S subunit. In prokaryotic cells, these subunits are named the 30S and 50S subunits, respectively. The ribosome's overall structure resembles a "doughnut" or a "cotton reel," with grooves and binding sites for various factors involved in protein synthesis.
Ribosomes can be found floating freely within the cytoplasm of cells or attached to the endoplasmic reticulum (ER) membrane, forming part of the rough ER. Membrane-bound ribosomes are responsible for synthesizing proteins that will be transported across the ER and ultimately secreted from the cell or inserted into the membrane. In contrast, cytoplasmic ribosomes synthesize proteins destined for use within the cytoplasm or organelles.
In summary, ribosomes are essential components of cells that facilitate protein synthesis by translating mRNA into functional polypeptide chains. They can be found in various cellular locations and exist as either free-floating entities or membrane-bound structures.
"Poly dA-dT" is not a medical term, but rather a molecular biology term that refers to a synthetic double-stranded DNA molecule. It is composed of two complementary strands: one strand consists of repeated adenine (dA) nucleotides, while the other strand consists of repeated thymine (dT) nucleotides. The "poly" prefix indicates that multiple units of these nucleotides are linked together in a chain-like structure.
This type of synthetic DNA molecule is often used as a substrate for various molecular biology techniques, such as in vitro transcription or translation assays, where it serves as a template for the production of RNA or proteins. It can also be used to study the interactions between DNA and proteins, such as transcription factors, that bind specifically to certain nucleotide sequences.
Poly(ADP-ribose) (PAR) is not strictly referred to as "Poly Adenosine Diphosphate Ribose" in the medical or biochemical context, although the term ADP-ribose is a component of it. Poly(ADP-ribose) is a polymer of ADP-ribose units that are synthesized by enzymes called poly(ADP-ribose) polymerases (PARPs).
Poly(ADP-ribosyl)ation, the process of adding PAR polymers to target proteins, plays a crucial role in various cellular processes such as DNA repair, genomic stability, and cell death. In medical research, alterations in PAR metabolism have been implicated in several diseases, including cancer and neurodegenerative disorders. Therefore, understanding the function and regulation of poly(ADP-ribose) is of significant interest in biomedical sciences.
I'm sorry for any confusion, but "Poly G" does not have a specific medical definition. The term "poly" is a prefix in medicine that means many or multiple, and "G" could potentially refer to a variety of things (such as a genetic locus or a grade), but without more context it's impossible to provide an accurate medical definition for this term.
If you have a specific medical question or concern, I would be happy to try to help you with that. Please provide some additional context or clarify what you mean by "Poly G."
I'm sorry for any confusion, but "Poly I" is not a recognized medical term or abbreviation in the context of human diseases or conditions. It's possible that there might be a typo or misunderstanding in your query. If you intended to ask about a specific medical condition, medication, or concept, please provide the full and correct term so I can give you an accurate and helpful response.
I'm sorry for any confusion, but "Poly T" is not a standard medical term that I am aware of. It is possible that it could be an abbreviation or shorthand used in a specific context, such as a medical report or research study. If you have more information about where this term came from or how it is being used, I may be able to provide a more accurate and helpful response.
However, if "Poly T" is meant to refer to polycythemia vera, which is a type of blood cancer characterized by an overproduction of red blood cells, then here's the definition:
Polycythemia Vera (PV) is a myeloproliferative neoplasm (MPN), a type of blood cancer that affects the bone marrow. In PV, the body produces too many red blood cells, white blood cells, and platelets, leading to an increased risk of blood clots, enlargement of the spleen, and other complications. The exact cause of PV is not known, but it is thought to be related to genetic mutations that affect the regulation of cell growth and division in the bone marrow. Symptoms of PV can include fatigue, headache, dizziness, shortness of breath, and a bluish or reddish tint to the skin. Treatment for PV typically involves medications to reduce the production of blood cells, as well as regular monitoring to manage complications and prevent progression of the disease.
I'm sorry for any confusion, but "Polydeoxyribonucleotides" is not a widely recognized or established medical term. It seems to be a made-up or very obscure term that combines "poly," meaning many, "deoxy," referring to the lack of a hydroxyl group at the 2' carbon position in the ribose sugar, and "ribonucleotides," which are the building blocks of RNA.
If you meant "Polydeoxynucleotides" instead, it would refer to long, synthetic chains of deoxynucleotides, which are the building blocks of DNA. These chains can be used in various biochemical and biological research applications, such as studying enzyme mechanisms or constructing genetic circuits.
Polyribonucleotides are long, chain-like molecules composed of multiple ribonucleotide monomers. Ribonucleotides themselves consist of a ribose sugar, a phosphate group, and one of the four nitrogenous bases: adenine (A), uracil (U), guanine (G), or cytosine (C). In polyribonucleotides, these ribonucleotide monomers are linked together by ester bonds between the phosphate group of one monomer and the ribose sugar of another.
These molecules play crucial roles in various biological processes, such as encoding genetic information, regulating gene expression, catalyzing chemical reactions, and serving as structural components within cells. Some examples of polyribonucleotides include messenger RNA (mRNA), ribosomal RNA (rRNA), transfer RNA (tRNA), and small nuclear RNA (snRNA).
In a medical context, polyribonucleotides may be used in therapeutic applications, such as gene therapy or vaccines. For instance, synthetic mRNAs can be designed to encode specific proteins, which can then be introduced into cells to stimulate the production of those proteins for various purposes, including immunization against infectious diseases or cancer treatment.
A ribonucleoprotein, U1 small nuclear (U1 snRNP) is a type of small nuclear ribonucleoprotein (snRNP) particle that is found within the nucleus of eukaryotic cells. These complexes are essential for various aspects of RNA processing, particularly in the form of spliceosomes, which are responsible for removing introns from pre-messenger RNA (pre-mRNA) during the process of gene expression.
The U1 snRNP is composed of a small nuclear RNA (snRNA) molecule called U1 snRNA, several proteins, and occasionally other non-coding RNAs. The U1 snRNA contains conserved sequences that recognize and bind to specific sequences in the pre-mRNA, forming base pairs with complementary regions within the intron. This interaction is crucial for the accurate identification and removal of introns during splicing.
In addition to its role in splicing, U1 snRNP has been implicated in other cellular processes such as transcription regulation, RNA decay, and DNA damage response. Dysregulation or mutations in U1 snRNP components have been associated with various human diseases, including cancer and neurological disorders.
Polynucleotide adenylyltransferase is not a medical term per se, but rather a biological term used to describe an enzyme that catalyzes the addition of adenine residues to the 3'-hydroxyl end of polynucleotides. In other words, these enzymes transfer AMP (adenosine monophosphate) molecules to the ends of DNA or RNA strands, creating a chain of adenine nucleotides.
One of the most well-known examples of this class of enzyme is terminal transferase, which is often used in research settings for various molecular biology techniques such as adding homopolymeric tails to DNA molecules. It's worth noting that while these enzymes have important applications in scientific research, they are not typically associated with medical diagnoses or treatments.