Stimulation of protein synthesis by insulin in rat skeletal muscle
is accompanied by enhanced association of eukaryotic initiation
factors eif-4e and eif-4g.
Kimball, Scot R., Christine V. Jurasinski, John C. Lawrence, Jr.
[acute]a, and Leonard S. Jefferson.
Department of Cellular and Molecular Physiology, The Pennsylvania
State University, College of Medicine, Hershey, PA 17033, Department
of Molecular Biology and Pharmacology, Washington University School
of Medicine, St. Louis, MO 63110
APStracts 3:0382C, 1996.
Insulin stimulated protein synthesis in gastrocnemius muscle of
perfused rat hindlimb preparations by approximately twofold. The
stimulation of protein synthesis was associated with a 12-fold
increase in the amount of eukaryotic initiation factor eIF-4G bound
to the mRNA cap binding protein eIF-4E. In part, the increased
binding of eIF-4G to eIF-4E was a result of release of eIF-4E bound
to the translational regulator, PHAS-I, through a mechanism involving
enhanced phosphorylation of PHAS-I. However, the insulin-induced
association of eIF-4E and eIF-4G was not due to increased net
phosphorylation of eIF-4E because insulin decreased the amount
present in the phosphorylated form from 86% to 59% of total eIF-4E.
Overall, the results suggest that insulin stimulates protein
synthesis in gastrocnemius through a mechanism involving increased
binding of eIF-4G to eIF-4E which is in part due to phosphorylation
of PHAS-I resulting in a release eIF-4E from the inactive PHAS
-I[beta]eIF-4E complex.
Received 9 September 1996; accepted in final form 19 November
1996.
APS Manuscript Number C527-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996