Insulin receptors in cultured mouse retinal cells

The binding of 125I-insulin to uncloned and cloned cultures of mouse retinal cells has been investigated. At 15 degrees C, binding of the hormone reached a steady state by 60 min, while at 37 degrees C equilibrium was reached earlier but at a lower level than at 15 degrees C. Porcine insulin, porcine proinsulin and guinea pig insulin displaced labelled insulin in proportion to their known biological potency. A sharp pH dependence of the hormone binding was observed with an optimum at pH 7.8. The dissociation rate of the 125I-insulin was increased in the presence of unlabelled hormone, suggesting the existence of negative cooperatively in the insulin-receptor interaction. The availability of established retinal cell lines with insulin receptors should facilitate the study of the insulin-retina interactions in a controlled in vitro system.