Tissue distribution of insulin-like growth factor receptors in the turkey.

1. The distribution and relative insulin-like growth factor (IGF) binding capacities of membranes derived from 14 tissues of the turkey were examined. 2. Affinity cross-linking analyses using 125I]IGF-I and 125I]IGF-II with membranes derived from the liver, pectoralis major muscle, gizzard, heart and brain indicated that both IGFs interact with only type-I IGF receptors on these tissues. 3. There was no evidence for the existence of a type-II IGF receptor in any tissue. 4. Although considerable variation was detected in the molecular weights of the IGF receptor alpha subunits between tissues (112.2-132.9 kDa), these differences did not appear to influence receptor-ligand affinities.