Document Detail


Uptake and processing of serine: pyruvate aminotransferase precursor by rat liver mitochondria in vitro and in vivo.
MedLine Citation:
PMID:  6725236     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Processing and uptake of the precursor of serine: pyruvate aminotransferase [EC 2.6.1.51] by mitochondria were studied in vitro and in vivo. Serine: pyruvate aminotransferase was synthesized mainly on free ribosomes as judged by immunoprecipitation of puromycin-labeled nascent peptides prepared from free and bound ribosomes. The precursor of rat liver serine:pyruvate aminotransferase (pSPT) synthesized in vitro was post-translationally processed to an apparently mature form by isolated rat liver mitochondria. Available evidence indicated that the processed product was localized in the matrix of mitochondria. Mature serine:pyruvate aminotransferase did not inhibit the in vitro processing, suggesting that the extra peptide was necessary for the mitochondrial uptake of the precursor. In the livers of rats fed a vitamin B6-deficient high-protein diet, the induction by glucagon of serine:pyruvate aminotransferase occurred and most of the induced enzyme existed in mitochondria as the apo-form, suggesting that pSPT was taken up by mitochondria and processed in the apo-form under the conditions employed. In the in vitro system, on the other hand, the processing of pSPT proceeded both in the absence and presence of pyridoxal 5'-phosphate. Should the precursor also bind the prosthetic molecule, therefore, it would be transported into mitochondria in both the apo- and holo-forms. When isolated rat hepatocytes were labeled with [35S]methionine, labeled pSPT appeared in the cytosolic fraction and was transported rapidly into mitochondria in association with the processing. This uptake and processing were inhibited by a fluorescent laser dye, rhodamine 123, and the precursor accumulated in the cytosol in the presence of the dye.
Authors:
T Oda; A Ichiyama; S Miura; M Mori
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of biochemistry     Volume:  95     ISSN:  0021-924X     ISO Abbreviation:  J. Biochem.     Publication Date:  1984 Mar 
Date Detail:
Created Date:  1984-07-09     Completed Date:  1984-07-09     Revised Date:  2007-12-19    
Medline Journal Info:
Nlm Unique ID:  0376600     Medline TA:  J Biochem     Country:  JAPAN    
Other Details:
Languages:  eng     Pagination:  815-24     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Animals
Biological Transport
Enzyme Precursors / metabolism*
Immunochemistry
Male
Mitochondria, Liver / enzymology*
Protein Processing, Post-Translational
Pyridoxine / physiology
Rats
Rats, Inbred Strains
Subcellular Fractions / enzymology
Transaminases / metabolism*
Chemical
Reg. No./Substance:
0/Enzyme Precursors; 65-23-6/Pyridoxine; EC 2.6.1.-/Transaminases; EC 2.6.1.51/serine-pyruvate aminotransferase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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