期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1978
卷号：75
期号：2
页码：730-734
DOI：10.1073/pnas.75.2.730
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Total liver polysomes were isolated from rats that had fasted for 48 hr and that then had been re-fed a high-carbohydrate, fat-free diet for 20-24 hr. Indirect immunoprecipitation of the polysomes with purified antibody to rat liver fatty acid synthetase and deproteination on sodium dodecyl sulfate-containing sucrose gradients gave an RNA fraction which, when translated in a cell-free system derived from wheat germ, yielded a major polypeptide of apparent molecular weight 225,000 when the translation products were analyzed by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. The polypeptide was specifically precipitated with antibody against rat liver fatty acid synthetase and competed with unlabeled fatty acid synthetase for binding to the antibody. It was somewhat smaller than native fatty acid synthetase subunits (molecular weight 240,000). The peptide accounted for approximately 65% of the radioactive, antibody-precipitable product, the remainder being peptides in the molecular weight range 100,000-150,000. Synthesis of the polypeptide was optimized with respect to K+, Mg2+, and spermine concentrations. The quantity of fatty acid synthetase mRNA obtained by the above procedure and measured by translation was a function of the nutritional state of the animal. The relative activity in fasting rats compared to rats that were re-fed for 12 hr was 1:12. The data suggest that rat liver fatty acid synthetase is synthesized as intact subunits from a large mRNA molecule or molecules.
关键词：mRNA translation ; wheat germ cell-free system ; regulation of fatty acid synthetase
