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

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Abstract

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(i)/(Met) and its level of aminoacylation were measured in these conditions to determine whether methionyl-tRNA(i)/(Met) formation is a mechanism involved in the regulation of initiation. The extent of aminoacylation of tRNA(i)/(Met) 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(i)/(Met), 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(i)/(Met) was 80 ± 7% and the total tissue content of tRNA(i)/(Met) 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(i)/(Met) was 79 ± 4% and the total tissue content of tRNA(i)/(Met) was 2.0 ± 0.3% compared with values of 79 ± 5 and 2.0 ± 0.2% for control animals. The total quantity of amino acids bound to all species of tRNA in skeletal muscle from diabetic rats was reduced to 80% of control values but was similar to the reduction in total RNA content, suggesting that a decrease in tRNA content and not deacylation per se had occurred. Thus these data suggest that neither the extent of aminoacylation nor the total tissue content of tRNA(i)/(Met) plays a regulatory role in the inhibition of peptide-chain initiation under the conditions examined.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Volume264
Issue number2 27-2
StatePublished - Jan 1 1993

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RNA, Transfer, Met
Aminoacylation
Transfer RNA
Rats
Liver
Proteins
Tissue
Muscle
Skeletal Muscle
Tryptophan
Methionine
RNA
Defects
Peptides
Medical problems
Animals
Amino Acids

All Science Journal Classification (ASJC) codes

  • Endocrinology, Diabetes and Metabolism
  • Physiology
  • Physiology (medical)

Cite this

@article{cfc76dd68cf143bc8eba1321c5cd4c70,
title = "Aminoacylation of initiator methionyl-tRNA(i) under conditions inhibitory to initiation of protein synthesis",
abstract = "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(i)/(Met) and its level of aminoacylation were measured in these conditions to determine whether methionyl-tRNA(i)/(Met) formation is a mechanism involved in the regulation of initiation. The extent of aminoacylation of tRNA(i)/(Met) 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(i)/(Met), 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(i)/(Met) was 80 ± 7{\%} and the total tissue content of tRNA(i)/(Met) 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(i)/(Met) was 79 ± 4{\%} and the total tissue content of tRNA(i)/(Met) was 2.0 ± 0.3{\%} compared with values of 79 ± 5 and 2.0 ± 0.2{\%} for control animals. The total quantity of amino acids bound to all species of tRNA in skeletal muscle from diabetic rats was reduced to 80{\%} of control values but was similar to the reduction in total RNA content, suggesting that a decrease in tRNA content and not deacylation per se had occurred. Thus these data suggest that neither the extent of aminoacylation nor the total tissue content of tRNA(i)/(Met) plays a regulatory role in the inhibition of peptide-chain initiation under the conditions examined.",
author = "Ojamaa, {K. M.} and Scot Kimball and Jefferson, {Leonard {"}Jim{"}}",
year = "1993",
month = "1",
day = "1",
language = "English (US)",
volume = "264",
journal = "American Journal of Physiology",
issn = "0193-1849",
publisher = "American Physiological Society",
number = "2 27-2",

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T1 - Aminoacylation of initiator methionyl-tRNA(i) under conditions inhibitory to initiation of protein synthesis

AU - Ojamaa, K. M.

AU - Kimball, Scot

AU - Jefferson, Leonard "Jim"

PY - 1993/1/1

Y1 - 1993/1/1

N2 - 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(i)/(Met) and its level of aminoacylation were measured in these conditions to determine whether methionyl-tRNA(i)/(Met) formation is a mechanism involved in the regulation of initiation. The extent of aminoacylation of tRNA(i)/(Met) 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(i)/(Met), 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(i)/(Met) was 80 ± 7% and the total tissue content of tRNA(i)/(Met) 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(i)/(Met) was 79 ± 4% and the total tissue content of tRNA(i)/(Met) was 2.0 ± 0.3% compared with values of 79 ± 5 and 2.0 ± 0.2% for control animals. The total quantity of amino acids bound to all species of tRNA in skeletal muscle from diabetic rats was reduced to 80% of control values but was similar to the reduction in total RNA content, suggesting that a decrease in tRNA content and not deacylation per se had occurred. Thus these data suggest that neither the extent of aminoacylation nor the total tissue content of tRNA(i)/(Met) plays a regulatory role in the inhibition of peptide-chain initiation under the conditions examined.

AB - 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(i)/(Met) and its level of aminoacylation were measured in these conditions to determine whether methionyl-tRNA(i)/(Met) formation is a mechanism involved in the regulation of initiation. The extent of aminoacylation of tRNA(i)/(Met) 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(i)/(Met), 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(i)/(Met) was 80 ± 7% and the total tissue content of tRNA(i)/(Met) 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(i)/(Met) was 79 ± 4% and the total tissue content of tRNA(i)/(Met) was 2.0 ± 0.3% compared with values of 79 ± 5 and 2.0 ± 0.2% for control animals. The total quantity of amino acids bound to all species of tRNA in skeletal muscle from diabetic rats was reduced to 80% of control values but was similar to the reduction in total RNA content, suggesting that a decrease in tRNA content and not deacylation per se had occurred. Thus these data suggest that neither the extent of aminoacylation nor the total tissue content of tRNA(i)/(Met) plays a regulatory role in the inhibition of peptide-chain initiation under the conditions examined.

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