These pages are best viewed with Netscape version 3.0 or higher or Internet Explorer version 3.0 or higher. When viewed with other browsers, some characters or attributes may not be rendered correctly. Hybrids behave as IGF-IR rather than IR with respect to ligand binding affinity, receptor autophosphorylation, and hormone internalization and degradation.
Factors regulating hybrid formation in vivo are unknown.
To address this issue, we used a quantitative microwell-based immunoassay to measure hybrid receptor abundance in skeletal muscle of 11 normal subjects and 12 patients with insulinoma, a state of primary nongenetically determined hyperinsulinemia. These results indicate that insulin-induced IR downregulation may lead to the formation of a higher proportion of hybrid receptors, whose abundance is negatively correlated with in vivo insulin sensitivity.