spacer gif spacer gif spacer gif spacer gif spacer gif
QUICK SEARCH:   [advanced]


spacer gif
     Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents    

This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Poli, A.
Right arrow Articles by Seglen, P. O.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Poli, A.
Right arrow Articles by Seglen, P. O.

Journal of Cell Science, Vol 48, Issue 1 1-18, Copyright © 1981 by Company of Biologists

JOURNAL ARTICLES

Effects of insulin and anchorage on hepatocytic protein metabolism and amino acid transport

A Poli, PB Gordon, PE Schwarze, B Grinde and PO Seglen

Insulin partially inhibits endogenous protein degradation in isolated hepatocytes. The inhibition seems to specifically affect the lysosomal pathway of degradation, since it is not additive to the effects of lysosome inhibitors such as propylamine and leupeptin. The insulin effect is potentiated by intermediate concentrations of amino acids, but is largely abolished at high amino acid concentrations which suppress degradation maximally, suggesting that the hormone may exert its effect indirectly by acting upon the more basal amino acid control mechanism. Glucagon, which stimulates protein degradation, similarly displays its effect only in the presence of intermediate amino acid concentrations. The insulin inhibition is not affected by the aminotransferase inhibitor, aminooxyacetate, indicating that it is not due to interference with amino acid metabolism. Protein synthesis furthermore does not seem to be required, since a significant insulin effect can be seen in the presence of the protein synthesis inhibitor, cycloheximide. The issue is, however, complicated by the fact that cycloheximide itself inhibits protein degradation to approximately the same extent as does insulin. Insulin stimulates uptake of the amino acid alpha-aminoisobutyrate (AIB), but not the uptake of valine, indicating a specific stimulation of 'A'-type transport. Cycloheximide similarly stimulates AIB uptake, without completely obfuscating the transport effect of insulin. Neither protein synthesis, protein degradation, amino acid transport, nor the effects of insulin were affected by cell-to-substratum anchorage (attachment and spreading) in any detectable way.


This article has been cited by other articles:


Home page
 J. Biol. Chem.Home page
E. F. C. Blommaart, J. J. F. P. Luiken, P. J. E. Blommaart, G. M. van Woerkom, and A. J. Meijer
Phosphorylation of Ribosomal Protein S6 Is Inhibitory for Autophagy in Isolated Rat Hepatocytes
J. Biol. Chem., February 3, 1995; 270(5): 2320 - 2326.
[Abstract] [Full Text] [PDF]


© The Company of Biologists Ltd 1981