Insulin Binding on Cultured Chick Muscle Cells: Decrease in Binding Associated with Cell Fusion

Summary

Binding of ¹²⁵I-bovine and chicken insulin to cultured embryonic chick skeletal muscle cells was studied. Bovine and chicken insulin bound cultured cells with high affinities of 2.4 × 10⁹M^-1 and 4.8 × 10⁹M^-1 and low affinities of 2.4 × 10⁷M^-1 and 3.7 × 10⁷M^-1, respectively. Maximum insulin binding was achieved after 90 min of incubation at 20°C and the maximum value was maintained for an additional 3 hr. Insulin binding increased in a linear manner with increasing nuclei number over a 5-fold range. Maximum insulin binding per nuclei decreased as cell fusion increased between 24 and 72 hr in culture, primarily due to a decrease in the number of low affinity insulin receptors.

Key-Words:

Insulin Binding - Muscle - Myoblast - Myotube - Insulin