Insulin receptors in cultured mouse retinal cells

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Abstract
Summary The binding of125I-insulin to uncloned and cloned cultures of mouse retinal cells has been investigated. At 15° C, binding of the hormone reached a steady state by 60 min, while at 37° C equilibrium was reached earlier but at a lower level than at 15° 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 the125I-insulin was increased in the presence of unlabelled hormone, suggesting the existence of negative cooperativity 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.