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：1972
卷号：69
期号：8
页码：2351-2353
DOI：10.1073/pnas.69.8.2351
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The action of growth hormone on skeletal tissue is mediated through somatomedin, a low molecular weight peptide found in serum. This peptide, formerly known as "sulfation factor" or "thymidine factor," produces marked insulin-like effects in various target tissues. Since at least some of the metabolic effects of insulin on target cells are initiated by a highly specific interaction with receptors on cell membranes, this study was undertaken to determine whether somatomedin might interact with the same binding sites. It was found that somatomedin, at physiological concentrations, competes with 125I-labeled insulin for receptor sites on isolated fat cells, liver membranes, and isolated chondrocytes, and that the relative binding affinities of insulin and somatomedin reflect the in vitro biological potencies of the two hormones in these tissues. This is the first demonstration of a peptide other than insulin, proinsulin, or derivatives of insulin competing for insulin-binding sites, and implies a structural, as well as a functional, homology between somatomedin and insulin. Somatomedin may be only one of a larger group of homologous pleiotypic peptides with different target organ specificities.
