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：1977
卷号：74
期号：9
页码：3647-3651
DOI：10.1073/pnas.74.9.3647
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The biosynthesis of {beta}-nerve growth factor ({beta}NGF) was studied in mouse submaxillary glands incubated with L-[35S]cystine. {beta}NGF was isolated from tissue extracts by the addition of antiserum against {beta}NGF and the washed immunoprecipitates were analyzed by sodium dodecyl sulfate gel electrophoresis. With short labeling periods (10 and 25 min) there is a major labeled species with an apparent molecular weight of 22,000 and a smaller peak comigrating with purified {beta}NGF chains (13,260). As time proceeds, the radioactivity in the 22,000 molecular weight peak plateaus, while the label in {beta}NGF continues to increase, until by 4 hr it greatly exceeds the radioactivity of the 22,000 molecular weight species. When glands incubated for 10 min are transferred to medium containing a large excess of unlabeled L-cystine, the 22,000 molecular weight peak gradually declines, and there is a corresponding increase in radioactivity at the {beta}NGF position. The 22,000 molecular weight species isolated from sodium dodecyl sulfate gels possesses all the cystine-containing peptides of {beta}NGF, and possibly two additional ones. When immunoprecipitates from submaxillary glands labeled for 25 min are incubated with the {gamma} subunit (a specific arginyl-esteropeptidase associated with {beta}NGF in the 7S NGF complex), the radioactivity in the 22,000 molecular weight species is converted to the {beta}NGF position. The results suggest that the 22,000 molecular weight species is a biosynthetic precursor to {beta}NGF, and that the {gamma} subunit may function as a specific protease in the processing event.
