| Control of hepatic proteolysis by leucine and isovaleryl-L-carnitine through a common locus. Evidence for a possible mechanism of recognition at the plasma membrane. | |
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MedLine Citation:
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PMID: 1429558 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Deprivation-induced proteolysis in the perfused rat liver is controlled through the multiphasic action of 7 regulatory amino acids of which L-leucine plays the dominant role. Recently, isovaleryl-L-carnitine (IVC) was shown to mimic the leucine's effects, suggesting that the two molecules share structural features that are recognized at a common site(s). In this study we find that each evokes identical responses consisting of inhibitory effects at 0.08 and 0.8 mM, separated by a sharp zonal loss of inhibition at 0.15 mM. As monitored by density shifts of beta-hexosaminidase in colloidal silica gradients, macroautophagy is suppressed by both. Responses to Leu and IVC at 0.08 and 0.15 mM are stereospecific and require a reactive group at the alpha-carbon (or equivalent) and a high degree of branched chain specificity. In addition, 0.5 mM Ala coregulates with IVC and Leu by decreasing the zonal loss at 0.15 mM. The fact that the multiphasic responses can be duplicated with equimolar mixtures of Leu + IVC indicates that both react at the same site(s). IVC is readily taken up by a saturable process, but owing to its rapid hydrolysis in the cell, the ratio of internal to external IVC remains low over a 4-fold concentration range. These findings, together with a kinetic analysis of concerted responses to regulatory amino acids, suggest that the recognition sites are at a position in the cell, possibly at the plasma membrane, to react reversibly with plasma amino acids. |
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Authors:
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G Miotto; R Venerando; K K Khurana; N Siliprandi; G E Mortimore |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: The Journal of biological chemistry Volume: 267 ISSN: 0021-9258 ISO Abbreviation: J. Biol. Chem. Publication Date: 1992 Nov |
Date Detail:
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Created Date: 1992-12-01 Completed Date: 1992-12-01 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 2985121R Medline TA: J Biol Chem Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 22066-72 Citation Subset: IM |
Affiliation:
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Department of Cellular and Molecular Physiology, College of Medicine, Pennsylvania State University, Hershey 17033. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Alanine
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metabolism Animals Biological Transport Carnitine / analogs & derivatives*, metabolism Cell Membrane / metabolism Glutamine / metabolism Kinetics Leucine / metabolism* Liver / metabolism* Proteins / metabolism* Rats |
| Grant Support | |
ID/Acronym/Agency:
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DK 21624/DK/NIDDK NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Proteins; 31023-24-2/3-methylbutyrylcarnitine; 541-15-1/Carnitine; 56-41-7/Alanine; 56-85-9/Glutamine; 61-90-5/Leucine |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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