Abstract
The growth promoting and insulin-like actions of somatomedin-C (Sm-C) are thought to be mediated respectively by interactions with the Sm-C and insulin (In) receptors. Since Sm-C and In are structurally homologous, we compared the size and subunit structure of their respective radiolabeled receptors in human placental membranes (hPM) and bovine chondrocytes (bC) by crosslinking with disuccinimidyl suberate (DSS). The labeled hormone-receptor complexes (RCs) were analyzed by SDS polyacrylamide gel electrophoresis (PAGE) and autoradiography. Specificity of the respective RCs was demonstrated by competitive inhibition studies. Both hPM RCs had apparent molecular weights of > 250,000 daltons. Reduction with 2-mercaptoethanol yielded subunits of ~ 140,000 daltons. Limited proteolysis with trypsin, chymotrypsin and staphylococcal V-8 protease of the labeled RCs gave similar products. The Sm-C RC In bC isolated from calf epiphyseal plates also contained a 140,000 dalton binding subunit indistinguishable from the HPM receptor. Conclusions: 1) the hPM receptor for Sm-C has a 140,000 MW binding subunit linked by disulfide bonds. 2) By this technique, the hPM Sm-C receptor is structurally indistinguishable from either the Sm-C receptor in bC or the In receptor in hPMs, 3) The sizes of In and Sm-C receptors and their subunits differ from that reported for MSA and certain other hormones.
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Chernausek, S., Trippel, S., Van Wyk, J. et al. Structural Similarity of Human and Bovine Somatomedin Receptors and Human Insulin Receptor: Analysis by Affinity Labeling. Pediatr Res 15, 1549 (1981). https://doi.org/10.1203/00006450-198112000-00082
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DOI: https://doi.org/10.1203/00006450-198112000-00082
