Distribution of insulin-like growth factor receptors in rat intestinal epithelium.

In summary, we present data from affinity cross-linking and Scatchard plot analysis that demonstrates the presence of both IGF-I receptors and IGF-II receptors on the brush border membranes of rat intestinal mucosa. The brush border location of the IGF receptors suggests that IGFs available in the intestinal lumen may initiate signal transduction events by binding to receptors displayed on the mucosal lining. Our findings provide further support for the notion that at least some of the mitogenic stimulus for rapid proliferation of intestinal epithelium arises from lumenal IGFs, which may be supplied by apical secretions from the mucosa, or in saliva, colostrum, milk, chyme, or bile.