Receptors for insulin and IGF-I in bovine lens epithelium

The presence of insulin receptors has not yet been established in lens epithelial cells. Our goal was to understand the involvement of insulin in lens pathology, especially diabetic cataractogenesis. As a first step in this process, we evaluated the presence of insulin receptors in bovine lens epithelium. Insulin bound to insulin receptor with a high affinity (KD 7.0 nM), although this binding of insulin to its receptor could be replaced by IGF-I (KD 41 nM). Similarly IGF-I binding to IGF-I receptor (KD 0.38 nM) could be inhibited by insulin (KD 53.7 nM). SDS-PAGE and subsequent autoradiography of affinity labeled insulin receptor show the presence of a 130 kDa band, indicating that the lens epithelium insulin receptor may be similar to insulin receptors isolated from other tissues.