Aminoacylation of initiator methionyl-tRNA(i) under conditions inhibitory to initiation of protein synthesis. 1993

K M Ojamaa, and S R Kimball, and L S Jefferson
Department of Cellular and Molecular Physiology, College of Medicine, Pennsylvania State University, Hershey 17033.

Inhibition of protein synthesis in perfused rat liver deprived of either methionine or tryptophan results from a defect in peptide-chain initiation. Similarly, the decreased rate of protein synthesis in liver from rats deprived of food for 24 h and in skeletal muscle after 2 days of diabetes results from a defect in initiation. In the present study, the tissue content of tRNA(iMet) and its level of aminoacylation were measured in these conditions to determine whether methionyl-tRNA(iMet) formation is a mechanism involved in the regulation of initiation. The extent of aminoacylation of tRNA(iMet) in livers perfused with supplemented medium or medium deficient in either methionine or tryptophan was 64 +/- 2, 61 +/- 3, and 66 +/- 2% of the total accepting activity, respectively. The total tissue content of tRNA(iMet), expressed as a percentage of total RNA, was 1.7 +/- 0.1, 1.6 +/- 0.1, and 1.6 +/- 0.1 for the three conditions, respectively. In livers from starved rats, the extent of aminoacylation of tRNA(iMet) was 80 +/- 7% and the total tissue content of tRNA(iMet) was 1.9 +/- 0.1% compared with control values of 82 +/- 6 and 2.0 +/- 0.1%, respectively. In skeletal muscle from diabetic rats, the extent of aminoacylation of tRNA(iMet) was 79 +/- 4% and the total tissue content of tRNA(iMet) was 2.0 +/- 0.3% compared with values of 79 +/- 5 and 2.0 +/- 0.2% for control animals.(ABSTRACT TRUNCATED AT 250 WORDS)

UI MeSH Term Description Entries
D008099 Liver A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances. Livers
D008297 Male Males
D009132 Muscles Contractile tissue that produces movement in animals. Muscle Tissue,Muscle,Muscle Tissues,Tissue, Muscle,Tissues, Muscle
D011506 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. Gene Products, Protein,Gene Proteins,Protein,Protein Gene Products,Proteins, Gene
D005508 Food Deprivation The withholding of food in a structured experimental situation. Deprivation, Food,Deprivations, Food,Food Deprivations
D000215 Acylation The addition of an organic acid radical into a molecule.
D000596 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. Amino Acid,Acid, Amino,Acids, Amino
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D012358 RNA, Transfer, Met A transfer RNA which is specific for carrying methionine to sites on the ribosomes. During initiation of protein synthesis, tRNA(f)Met in prokaryotic cells and tRNA(i)Met in eukaryotic cells binds to the start codon (CODON, INITIATOR). Initiator tRNA,Methionine-Specific tRNA,Methionine-Specific tRNAm,RNA, Transfer, Initiator,Transfer RNA, Met,tRNA(f)Met,tRNA(i)Met,tRNA(m)Met,tRNAMet,tRNA(Met),Met Transfer RNA,Methionine Specific tRNA,Methionine Specific tRNAm,RNA, Met Transfer,tRNA, Initiator,tRNA, Methionine-Specific,tRNAm, Methionine-Specific
D015852 Eukaryotic Initiation Factor-2 Eukaryotic initiation factor of protein synthesis. In higher eukaryotes the factor consists of three subunits: alpha, beta, and gamma. As initiation proceeds, eIF-2 forms a ternary complex with Met-tRNAi and GTP. EIF-2,Peptide Initiation Factor EIF-2,EIF-2 alpha,EIF-2 beta,EIF-2 gamma,EIF-2alpha,EIF-2beta,EIF-2gamma,EIF2,Eukaryotic Initiation Factor-2, alpha Subunit,Eukaryotic Initiation Factor-2, beta Subunit,Eukaryotic Initiation Factor-2, gamma Subunit,Eukaryotic Peptide Initiation Factor-2,EIF 2,EIF 2 alpha,EIF 2 beta,EIF 2 gamma,EIF 2alpha,EIF 2beta,EIF 2gamma,Eukaryotic Initiation Factor 2,Eukaryotic Initiation Factor 2, alpha Subunit,Eukaryotic Initiation Factor 2, beta Subunit,Eukaryotic Initiation Factor 2, gamma Subunit,Eukaryotic Peptide Initiation Factor 2,Initiation Factor-2, Eukaryotic,Peptide Initiation Factor EIF 2

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