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：10
页码：4719-4723
DOI：10.1073/pnas.75.10.4719
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：When isolated rat pars intermedia cells were incubated for 10 min with radioactive amino acids, one major labeled protein with a molecular weight of 30,000 +/- 1500 was extracted. This protein was shown to contain in its sequence the antigenic determinants for corticotropin and beta-melanotropin by immunoprecipitation. When the radioactivity incorporated into this large molecular weight protein during the first 10 min was chased by a further incubation in presence of an excess of unlabeled amino acid, the initial protein was degraded into several smaller peptides including beta-endorphin and beta-lipotropin. Another 18,000-dalton peptide was also observed and was tentatively identified as a large molecular form of corticotropin. From the kinetics of the maturation of the initial precursor, it is concluded that the initial cleavage of the 30,000-dalton peptide gives rise to beta-lipotropin and the 18,000-dalton form of corticotropin. beta-Lipotropin is subsequently cleaved to form beta-endorphin.
