Leucine Zippers: DNA-binding motifs formed from two alpha-helixes which intertwine for about eight turns into a coiled coil and then bifurcate to form Y shaped structures. Leucines occurring in heptad repeats end up on the same sides of the helixes and are adjacent to each other in the stem of the Y (the "zipper" region). The DNA-binding residues are located in the bifurcated region of the Y.Leucyl Aminopeptidase: A zinc containing enzyme of the hydrolase class that catalyzes the removal of the N-terminal amino acid from most L-peptides, particularly those with N-terminal leucine residues but not those with N-terminal lysine or arginine residues. This occurs in tissue cell cytosol, with high activity in the duodenum, liver, and kidney. The activity of this enzyme is commonly assayed using a leucine arylamide chromogenic substrate such as leucyl beta-naphthylamide.Keto AcidsIsoleucine: An essential branched-chain aliphatic amino acid found in many proteins. It is an isomer of LEUCINE. It is important in hemoglobin synthesis and regulation of blood sugar and energy levels.Amino Acids: Organic compounds that generally contain an amino (-NH2) and a carboxyl (-COOH) group. Twenty alpha-amino acids are the subunits which are polymerized to form proteins.Leucine Dehydrogenase: An octameric enzyme belonging to the superfamily of amino acid dehydrogenases. Leucine dehydrogenase catalyzes the reversible oxidative deamination of L-LEUCINE, to 4-methyl-2-oxopentanoate (2-ketoisocaproate) and AMMONIA, with the corresponding reduction of the cofactor NAD+.Amino Acids, Branched-Chain: Amino acids which have a branched carbon chain.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.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.Valine: A branched-chain essential amino acid that has stimulant activity. It promotes muscle growth and tissue repair. It is a precursor in the penicillin biosynthetic pathway.Basic-Leucine Zipper Transcription Factors: A large superfamily of transcription factors that contain a region rich in BASIC AMINO ACID residues followed by a LEUCINE ZIPPER domain.Leucine Transaminase: A PYRIDOXAL PHOSPHATE containing enzyme that catalyzes the reversible transamination of branched-chain AMINO ACIDS to 2-oxoglutarate.2-Isopropylmalate Synthase: An enzyme that catalyzes the first step in the biosynthetic pathway to LEUCINE, forming isopropyl malate from acetyl-CoA and alpha-ketoisovaleric acid. This enzyme was formerly listed as EC An essential aromatic amino acid that is a precursor of MELANIN; DOPAMINE; noradrenalin (NOREPINEPHRINE), and THYROXINE.Carbon Isotopes: Stable carbon atoms that have the same atomic number as the element carbon, but differ in atomic weight. C-13 is a stable carbon isotope.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Kinetics: The rate dynamics in chemical or physical systems.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.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, Transfer, Leu: A transfer RNA which is specific for carrying leucine to sites on the ribosomes in preparation for protein synthesis.Norleucine: An unnatural amino acid that is used experimentally to study protein structure and function. It is structurally similar to METHIONINE, however it does not contain SULFUR.Proteins: Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein.Amino Acids, Essential: Amino acids that are not synthesized by the human body in amounts sufficient to carry out physiological functions. They are obtained from dietary foodstuffs.Mutagenesis, Site-Directed: Genetically engineered MUTAGENESIS at a specific site in the DNA molecule that introduces a base substitution, or an insertion or deletion.Glutamine: A non-essential amino acid present abundantly throughout the body and is involved in many metabolic processes. It is synthesized from GLUTAMIC ACID and AMMONIA. It is the principal carrier of NITROGEN in the body and is an important energy source for many cells.Alanine: A non-essential amino acid that occurs in high levels in its free state in plasma. It is produced from pyruvate by transamination. It is involved in sugar and acid metabolism, increases IMMUNITY, and provides energy for muscle tissue, BRAIN, and the CENTRAL NERVOUS SYSTEM.DNA-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.Transcription Factors: Endogenous substances, usually proteins, which are effective in the initiation, stimulation, or termination of the genetic transcription process.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.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.Nitrogen: An element with the atomic symbol N, atomic number 7, and atomic weight [14.00643; 14.00728]. Nitrogen exists as a diatomic gas and makes up about 78% of the earth's atmosphere by volume. It is a constituent of proteins and nucleic acids and found in all living cells.G-Box Binding Factors: A family of transcription factors found primarily in PLANTS that bind to the G-box DNA sequence CACGTG or to a consensus sequence CANNTG.Caproates: Derivatives of caproic acid. Included under this heading are a broad variety of acid forms, salts, esters, and amides that contain a carboxy terminated six carbon aliphatic structure.Dimerization: The process by which two molecules of the same chemical composition form a condensation product or polymer.Pentanoic AcidsInsulin: A 51-amino acid pancreatic hormone that plays a major role in the regulation of glucose metabolism, directly by suppressing endogenous glucose production (GLYCOGENOLYSIS; GLUCONEOGENESIS) and indirectly by suppressing GLUCAGON secretion and LIPOLYSIS. Native insulin is a globular protein comprised of a zinc-coordinated hexamer. Each insulin monomer containing two chains, A (21 residues) and B (30 residues), linked by two disulfide bonds. Insulin is used as a drug to control insulin-dependent diabetes mellitus (DIABETES MELLITUS, TYPE 1).Binding Sites: The parts of a macromolecule that directly participate in its specific combination with another molecule.Muscle Proteins: The protein constituents of muscle, the major ones being ACTINS and MYOSINS. More than a dozen accessory proteins exist including TROPONIN; TROPOMYOSIN; and DYSTROPHIN.Leucine-tRNA Ligase: An enzyme that activates leucine with its specific transfer RNA. EC A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).Transaminases: A subclass of enzymes of the transferase class that catalyze the transfer of an amino group from a donor (generally an amino acid) to an acceptor (generally a 2-keto acid). Most of these enzymes are pyridoxyl phosphate proteins. (Dorland, 28th ed) EC 2.6.1.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.Nutritional Requirements: The amounts of various substances in food needed by an organism to sustain healthy life.Proline: A non-essential amino acid that is synthesized from GLUTAMIC ACID. It is an essential component of COLLAGEN and is important for proper functioning of joints and tendons.Carbon Radioisotopes: Unstable isotopes of carbon that decay or disintegrate emitting radiation. C atoms with atomic weights 10, 11, and 14-16 are radioactive carbon isotopes.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.TritiumPellagra: A disease due to deficiency of NIACIN, a B-complex vitamin, or its precursor TRYPTOPHAN. It is characterized by scaly DERMATITIS which is often associated with DIARRHEA and DEMENTIA (the three D's).Dietary Proteins: Proteins obtained from foods. They are the main source of the ESSENTIAL AMINO ACIDS.Amino Acid Substitution: The naturally occurring or experimentally induced replacement of one or more AMINO ACIDS in a protein with another. If a functionally equivalent amino acid is substituted, the protein may retain wild-type activity. Substitution may also diminish, enhance, or eliminate protein function. Experimentally induced substitution is often used to study enzyme activities and binding site properties.Cell Line: Established cell cultures that have the potential to propagate indefinitely.Lysine: An essential amino acid. It is often added to animal feed.Leucine-Responsive Regulatory Protein: A LEUCINE and DNA-binding protein that is found primarily in BACTERIA and ARCHAEA. It regulates GENETIC TRANSCRIPTION involved in METABOLISM of AMINO ACIDS in response to the increased concentration of LEUCINE.Methionine: A sulfur-containing essential L-amino acid that is important in many body functions.Glucose: A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement.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.Liver: A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.Oxo-Acid-Lyases: Enzymes that catalyze the cleavage of a carbon-carbon bond of a 3-hydroxy acid. (Dorland, 28th ed) EC 4.1.3.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.Threonine: An essential amino acid occurring naturally in the L-form, which is the active form. It is found in eggs, milk, gelatin, and other proteins.3-Isopropylmalate Dehydrogenase: An NAD+ dependent enzyme that catalyzes the oxidation of 3-carboxy-2-hydroxy-4-methylpentanoate to 3-carboxy-4-methyl-2-oxopentanoate. It is involved in the biosynthesis of VALINE; LEUCINE; and ISOLEUCINE.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).Biological Transport: The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.Models, Molecular: Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.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).Cystinyl Aminopeptidase: A zinc-containing sialoglycoprotein that is used to study aminopeptidase activity in the pathogenesis of hypertension. EC Dehydrogenase: A mitochondrial flavoprotein, this enzyme catalyzes the oxidation of 3-methylbutanoyl-CoA to 3-methylbut-2-enoyl-CoA using FAD as a cofactor. Defects in the enzyme, is associated with isovaleric acidemia (IVA).Deuterium: Deuterium. The stable isotope of hydrogen. It has one neutron and one proton in the nucleus.Basic Helix-Loop-Helix Leucine Zipper Transcription Factors: A family of transcription factors that contain regions rich in basic residues, LEUCINE ZIPPER domains, and HELIX-LOOP-HELIX MOTIFS.Recombinant Proteins: Proteins prepared by recombinant DNA technology.Glycine: A non-essential amino acid. It is found primarily in gelatin and silk fibroin and used therapeutically as a nutrient. It is also a fast inhibitory neurotransmitter.Peptides: Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are linear polypeptides that are normally synthesized on RIBOSOMES.Bacterial Proteins: Proteins found in any species of bacterium.Muscle, Skeletal: A subtype of striated muscle, attached by TENDONS to the SKELETON. Skeletal muscles are innervated and their movement can be consciously controlled. They are also called voluntary muscles.Nitrogen Isotopes: Stable nitrogen atoms that have the same atomic number as the element nitrogen, but differ in atomic weight. N-15 is a stable nitrogen isotope.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.Aminopeptidases: A subclass of EXOPEPTIDASES that act on the free N terminus end of a polypeptide liberating a single amino acid residue. EC 3.4.11.Dicarboxylic AcidsDecarboxylation: The removal of a carboxyl group, usually in the form of carbon dioxide, from a chemical compound.TOR Serine-Threonine Kinases: A serine threonine kinase that controls a wide range of growth-related cellular processes. The protein is referred to as the target of RAPAMYCIN due to the discovery that SIROLIMUS (commonly known as rapamycin) forms an inhibitory complex with TACROLIMUS BINDING PROTEIN 1A that blocks the action of its enzymatic activity.Electrophoresis, Polyacrylamide Gel: Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.Protein Structure, Secondary: The level of protein structure in which regular hydrogen-bond interactions within contiguous stretches of polypeptide chain give rise to alpha helices, beta strands (which align to form beta sheets) or other types of coils. This is the first folding level of protein conformation.Tryptophan: An essential amino acid that is necessary for normal growth in infants and for NITROGEN balance in adults. It is a precursor of INDOLE ALKALOIDS in plants. It is a precursor of SEROTONIN (hence its use as an antidepressant and sleep aid). It can be a precursor to NIACIN, albeit inefficiently, in mammals.Carrier Proteins: Transport proteins that carry specific substances in the blood or across cell membranes.3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide): A ketone oxidoreductase that catalyzes the overall conversion of alpha-keto acids to ACYL-CoA and CO2. The enzyme requires THIAMINE DIPHOSPHATE as a cofactor. Defects in genes that code for subunits of the enzyme are a cause of MAPLE SYRUP URINE DISEASE. The enzyme was formerly classified as EC 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.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.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.Acetolactate Synthase: A flavoprotein enzyme that catalyzes the formation of acetolactate from 2 moles of PYRUVATE in the biosynthesis of VALINE and the formation of acetohydroxybutyrate from pyruvate and alpha-ketobutyrate in the biosynthesis of ISOLEUCINE. This enzyme was formerly listed as EC Specificity: A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.Hydro-Lyases: Enzymes that catalyze the breakage of a carbon-oxygen bond leading to unsaturated products via the removal of water. EC 4.2.1.Proto-Oncogene Proteins c-jun: Cellular DNA-binding proteins encoded by the c-jun genes (GENES, JUN). They are involved in growth-related transcriptional control. There appear to be three distinct functions: dimerization (with c-fos), DNA-binding, and transcriptional activation. Oncogenic transformation can take place by constitutive expression of c-jun.DNA, Complementary: Single-stranded complementary DNA synthesized from an RNA template by the action of RNA-dependent DNA polymerase. cDNA (i.e., complementary DNA, not circular DNA, not C-DNA) is used in a variety of molecular cloning experiments as well as serving as a specific hybridization probe.Amino Acid Motifs: Commonly observed structural components of proteins formed by simple combinations of adjacent secondary structures. A commonly observed structure may be composed of a CONSERVED SEQUENCE which can be represented by a CONSENSUS SEQUENCE.Amino Acid Transport Systems: Cellular proteins and protein complexes that transport amino acids across biological membranes.Point Mutation: A mutation caused by the substitution of one nucleotide for another. This results in the DNA molecule having a change in a single base pair.Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.Ribosomal Protein S6 Kinases: A family of protein serine/threonine kinases which act as intracellular signalling intermediates. Ribosomal protein S6 kinases are activated through phosphorylation in response to a variety of HORMONES and INTERCELLULAR SIGNALING PEPTIDES AND PROTEINS. Phosphorylation of RIBOSOMAL PROTEIN S6 by enzymes in this class results in increased expression of 5' top MRNAs. Although specific for RIBOSOMAL PROTEIN S6 members of this class of kinases can act on a number of substrates within the cell. The immunosuppressant SIROLIMUS inhibits the activation of ribosomal protein S6 kinases.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Oncogene Protein p65(gag-jun): Transforming protein coded by jun oncogenes (GENES, JUN). This is a gag-onc fusion protein of about 65 kDa derived from avian sarcoma virus. v-jun lacks a negative regulatory domain that regulates transcription in c-jun.Urea: A compound formed in the liver from ammonia produced by the deamination of amino acids. It is the principal end product of protein catabolism and constitutes about one half of the total urinary solids.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.Amino Acids, Cyclic: A class of amino acids characterized by a closed ring structure.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.Biological Transport, Active: The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy.Rats, Inbred Strains: Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations or by parent x offspring matings carried out with certain restrictions. This also includes animals with a long history of closed colony breeding.Enzyme Repression: The interference in synthesis of an enzyme due to the elevated level of an effector substance, usually a metabolite, whose presence would cause depression of the gene responsible for enzyme synthesis.Hyperammonemia: Elevated level of AMMONIA in the blood. It is a sign of defective CATABOLISM of AMINO ACIDS or ammonia to UREA.Arginine: An essential amino acid that is physiologically active in the L-form.Molecular Weight: The sum of the weight of all the atoms in a molecule.Isomerases: A class of enzymes that catalyze geometric or structural changes within a molecule to form a single product. The reactions do not involve a net change in the concentrations of compounds other than the substrate and the product.(from Dorland, 28th ed) EC 5.Ketone Oxidoreductases: Oxidoreductases that are specific for KETONES.Amino Acyl-tRNA Synthetases: A subclass of enzymes that aminoacylate AMINO ACID-SPECIFIC TRANSFER RNA with their corresponding AMINO ACIDS.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.Dietary Supplements: Products in capsule, tablet or liquid form that provide dietary ingredients, and that are intended to be taken by mouth to increase the intake of nutrients. Dietary supplements can include macronutrients, such as proteins, carbohydrates, and fats; and/or MICRONUTRIENTS, such as VITAMINS; MINERALS; and PHYTOCHEMICALS.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.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.Protein Kinases: A family of enzymes that catalyze the conversion of ATP and a protein to ADP and a phosphoprotein.Glutamate Dehydrogenase: An enzyme that catalyzes the conversion of L-glutamate and water to 2-oxoglutarate and NH3 in the presence of NAD+. (From Enzyme Nomenclature, 1992) EC 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.Performance-Enhancing Substances: Agents that improve the ability to carry out activities such as athletics, mental endurance, work, and resistance to stress. The substances can include PRESCRIPTION DRUGS; DIETARY SUPPLEMENTS; phytochemicals; and ILLICIT DRUGS.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.Culture Media: Any liquid or solid preparation made specifically for the growth, storage, or transport of microorganisms or other types of cells. The variety of media that exist allow for the culturing of specific microorganisms and cell types, such as differential media, selective media, test media, and defined media. Solid media consist of liquid media that have been solidified with an agent such as AGAR or GELATIN.Diet: Regular course of eating and drinking adopted by a person or animal.Carbon Dioxide: A colorless, odorless gas that can be formed by the body and is necessary for the respiration cycle of plants and animals.Triacetin: A triglyceride that is used as an antifungal agent.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)Signal Transduction: The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway.Cycloheximide: Antibiotic substance isolated from streptomycin-producing strains of Streptomyces griseus. It acts by inhibiting elongation during protein synthesis.Blood Glucose: Glucose in blood.Puromycin: A cinnamamido ADENOSINE found in STREPTOMYCES alboniger. It inhibits protein synthesis by binding to RNA. It is an antineoplastic and antitrypanosomal agent and is used in research as an inhibitor of protein synthesis.Mutagenesis: Process of generating a genetic MUTATION. It may occur spontaneously or be induced by MUTAGENS.Transcriptional Activation: Processes that stimulate the GENETIC TRANSCRIPTION of a gene or set of genes.Hydrogen-Ion Concentration: The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH = log 1/2[1/(H+)], where (H+) is the hydrogen ion concentration in gram equivalents per liter of solution. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Helix-Loop-Helix Motifs: Recurring supersecondary structures characterized by 20 amino acids folding into two alpha helices connected by a non-helical "loop" segment. They are found in many sequence-specific DNA-BINDING PROTEINS and in CALCIUM-BINDING PROTEINS.RNA, Transfer, Ser: A transfer RNA which is specific for carrying serine to sites on the ribosomes in preparation for protein synthesis.Plant Proteins: Proteins found in plants (flowers, herbs, shrubs, trees, etc.). The concept does not include proteins found in vegetables for which VEGETABLE PROTEINS is available.Fasting: Abstaining from all food.COS Cells: CELL LINES derived from the CV-1 cell line by transformation with a replication origin defective mutant of SV40 VIRUS, which codes for wild type large T antigen (ANTIGENS, POLYOMAVIRUS TRANSFORMING). They are used for transfection and cloning. (The CV-1 cell line was derived from the kidney of an adult male African green monkey (CERCOPITHECUS AETHIOPS).)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.Caseins: A mixture of related phosphoproteins occurring in milk and cheese. The group is characterized as one of the most nutritive milk proteins, containing all of the common amino acids and rich in the essential ones.Tyrosine: A non-essential amino acid. In animals it is synthesized from PHENYLALANINE. It is also the precursor of EPINEPHRINE; THYROID HORMONES; and melanin.Trans-Activators: Diffusible gene products that act on homologous or heterologous molecules of viral or cellular DNA to regulate the expression of proteins.Alcohol Oxidoreductases: A subclass of enzymes which includes all dehydrogenases acting on primary and secondary alcohols as well as hemiacetals. They are further classified according to the acceptor which can be NAD+ or NADP+ (subclass 1.1.1), cytochrome (1.1.2), oxygen (1.1.3), quinone (1.1.5), or another acceptor (1.1.99).Calorimetry, Indirect: Calculation of the energy expenditure in the form of heat production of the whole body or individual organs based on respiratory gas exchange.Swine: Any of various animals that constitute the family Suidae and comprise stout-bodied, short-legged omnivorous mammals with thick skin, usually covered with coarse bristles, a rather long mobile snout, and small tail. Included are the genera Babyrousa, Phacochoerus (wart hogs), and Sus, the latter containing the domestic pig (see SUS SCROFA).Codon: A set of three nucleotides in a protein coding sequence that specifies individual amino acids or a termination signal (CODON, TERMINATOR). Most codons are universal, but some organisms do not produce the transfer RNAs (RNA, TRANSFER) complementary to all codons. These codons are referred to as unassigned codons (CODONS, NONSENSE).Muscles: Contractile tissue that produces movement in animals.Cattle: Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.Dose-Response Relationship, Drug: The relationship between the dose of an administered drug and the response of the organism to the drug.Cell Membrane: The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.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.Ribosomal Protein S6 Kinases, 70-kDa: A family of ribosomal protein S6 kinases that are considered the major physiological kinases for RIBOSOMAL PROTEIN S6. Unlike RIBOSOMAL PROTEIN S6 KINASES, 90KDa the proteins in this family are sensitive to the inhibitory effects of RAPAMYCIN and contain a single kinase domain. They are referred to as 70kDa proteins, however ALTERNATIVE SPLICING of mRNAs for proteins in this class also results in 85kDa variants being formed.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.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.Amino Acids, Aromatic: Amino acids containing an aromatic side chain.Plasma Membrane Neurotransmitter Transport Proteins: A family of neurotransmitter transporter proteins that facilitate NEUROTRANSMITTER reuptake into PRESYNAPTIC TERMINALS. They may play a role in regulating the intensity and duration of neurotransmission.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.Chromatography, Gel: Chromatography on non-ionic gels without regard to the mechanism of solute discrimination.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.Amination: The creation of an amine. It can be produced by the addition of an amino group to an organic compound or reduction of a nitro group.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.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.Two-Hybrid System Techniques: Screening techniques first developed in yeast to identify genes encoding interacting proteins. Variations are used to evaluate interplay between proteins and other molecules. Two-hybrid techniques refer to analysis for protein-protein interactions, one-hybrid for DNA-protein interactions, three-hybrid interactions for RNA-protein interactions or ligand-based interactions. Reverse n-hybrid techniques refer to analysis for mutations or other small molecules that dissociate known interactions.Amino Acid Transport Systems, Neutral: Amino acid transporter systems capable of transporting neutral amino acids (AMINO ACIDS, NEUTRAL).Threonine Dehydratase: A pyridoxal-phosphate protein that catalyzes the deamination of THREONINE to 2-ketobutyrate and AMMONIA. The role of this enzyme can be biosynthetic or biodegradative. In the former role it supplies 2-ketobutyrate required for ISOLEUCINE biosynthesis, while in the latter it is only involved in the breakdown of threonine to supply energy. This enzyme was formerly listed as EC 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.Magnetic Resonance Spectroscopy: Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING).Saccharomyces: A genus of ascomycetous fungi of the family Saccharomycetaceae, order SACCHAROMYCETALES.Gas Chromatography-Mass Spectrometry: A microanalytical technique combining mass spectrometry and gas chromatography for the qualitative as well as quantitative determinations of compounds.Infusions, Intravenous: The long-term (minutes to hours) administration of a fluid into the vein through venipuncture, either by letting the fluid flow by gravity or by pumping it.Aminoisobutyric Acids: A group of compounds that are derivatives of the amino acid 2-amino-2-methylpropanoic acid.DNA Mutational Analysis: Biochemical identification of mutational changes in a nucleotide sequence.Histidine: An essential amino acid that is required for the production of HISTAMINE.PyruvatesDipeptides: Peptides composed of two amino acid units.Hydrophobic and Hydrophilic Interactions: The thermodynamic interaction between a substance and WATER.Parenteral Nutrition: The administering of nutrients for assimilation and utilization by a patient who cannot maintain adequate nutrition by enteral feeding alone. Nutrients are administered by a route other than the alimentary canal (e.g., intravenously, subcutaneously).Membrane Proteins: Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.Multienzyme Complexes: Systems of enzymes which function sequentially by catalyzing consecutive reactions linked by common metabolic intermediates. They may involve simply a transfer of water molecules or hydrogen atoms and may be associated with large supramolecular structures such as MITOCHONDRIA or RIBOSOMES.Restriction Mapping: Use of restriction endonucleases to analyze and generate a physical map of genomes, genes, or other segments of DNA.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.Peptide Biosynthesis: The production of PEPTIDES or PROTEINS by the constituents of a living organism. The biosynthesis of proteins on RIBOSOMES following an RNA template is termed translation (TRANSLATION, GENETIC). There are other, non-ribosomal peptide biosynthesis (PEPTIDE BIOSYNTHESIS, NUCLEIC ACID-INDEPENDENT) mechanisms carried out by PEPTIDE SYNTHASES and PEPTIDYLTRANSFERASES. Further modifications of peptide chains yield functional peptide and protein molecules.Carcinoma 256, Walker: A transplantable carcinoma of the rat that originally appeared spontaneously in the mammary gland of a pregnant albino rat, and which now resembles a carcinoma in young transplants and a sarcoma in older transplants. (Stedman, 25th ed)Rats, Sprague-Dawley: A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.Radioactive Tracers: Radioactive substances added in minute amounts to the reacting elements or compounds in a chemical process and traced through the process by appropriate detection methods, e.g., Geiger counter. Compounds containing tracers are often said to be tagged or labeled. (Hawley's Condensed Chemical Dictionary, 12th ed)Proto-Oncogene Proteins c-fos: Cellular DNA-binding proteins encoded by the c-fos genes (GENES, FOS). They are involved in growth-related transcriptional control. c-fos combines with c-jun (PROTO-ONCOGENE PROTEINS C-JUN) to form a c-fos/c-jun heterodimer (TRANSCRIPTION FACTOR AP-1) that binds to the TRE (TPA-responsive element) in promoters of certain genes.Energy Metabolism: The chemical reactions involved in the production and utilization of various forms of energy in cells.Chickens: Common name for the species Gallus gallus, the domestic fowl, in the family Phasianidae, order GALLIFORMES. It is descended from the red jungle fowl of SOUTHEAST ASIA.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.MAP Kinase Kinase Kinases: Mitogen-activated protein kinase kinase kinases (MAPKKKs) are serine-threonine protein kinases that initiate protein kinase signaling cascades. They phosphorylate MITOGEN-ACTIVATED PROTEIN KINASE KINASES; (MAPKKs) which in turn phosphorylate MITOGEN-ACTIVATED PROTEIN KINASES; (MAPKs).Crystallography, X-Ray: The study of crystal structure using X-RAY DIFFRACTION techniques. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Peptide Fragments: Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.Glucagon: A 29-amino acid pancreatic peptide derived from proglucagon which is also the precursor of intestinal GLUCAGON-LIKE PEPTIDES. Glucagon is secreted by PANCREATIC ALPHA CELLS and plays an important role in regulation of BLOOD GLUCOSE concentration, ketone metabolism, and several other biochemical and physiological processes. (From Gilman et al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 9th ed, p1511)Dipeptidases: EXOPEPTIDASES that specifically act on dipeptides. EC 3.4.13.Carbon-Carbon Ligases: Enzymes that catalyze the joining of two molecules by the formation of a carbon-carbon bond. These are the carboxylating enzymes and are mostly biotinyl-proteins. EC 6.4.Salmonella typhimurium: A serotype of Salmonella enterica that is a frequent agent of Salmonella gastroenteritis in humans. It also causes PARATYPHOID FEVER.Protein O-Methyltransferase: An enzyme that catalyzes the transfer of methyl groups from S-adenosylmethionine to free carboxyl groups of a protein molecule forming methyl esters. EC 2.1.1.-.Hydrolysis: The process of cleaving a chemical compound by the addition of a molecule of water.Isotope Labeling: Techniques for labeling a substance with a stable or radioactive isotope. It is not used for articles involving labeled substances unless the methods of labeling are substantively discussed. Tracers that may be labeled include chemical substances, cells, or microorganisms.