Specific binding sites for insulin have been identified and characterized for the human erythroleukemia cell line K-562. The binding of [125I]-insulin to the cells increased as a function of time, reaching a maximum at 20 min when incubation was performed at 37°C. The binding of [125I]-insulin was dose-dependently inhibited by insulin or proinsulin. Scatchard plot of the binding data was curvilinear, and the number of insulin receptors was approximately 39,000. Insulin at concentrations of 0.05–10.0 ng/ml stimulated CO2 production and DNA and protein synthesis in K-562 cells in a dose-dependent manner, indicating that the insulin binding sites are functionally important in mediating these biochemical events induced by insulin. Maximal insulin responses were elicited at concentrations of <5 ng/ml, when (at most) 10% of the insulin receptors were occupied. After binding to the cells, [125I]-insulin was degraded in a time- and temperature-dependent manner. As reported for other types of cells, unlabeled insulin also downregulated insulin receptors in K-562 cells. When the cells were incubated with 1 × 10−7 M unlabeled insulin for 24 h, the number of insulin receptors decreased by 50% without a change of affinity. K-562 cells may be useful in studying the role of insulin receptors in cell functions induced by insulin.
Characteristics of Insulin Receptors and Insulin Action in Human Myelogenous Leukemia Cell Line K-562
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Toshikazu Yamanouchi, Toshio Tsushima, Yasuo Akanuma, Masato Kasuga, Hideaki Mizoguchi, Fumimaro Takaku; Characteristics of Insulin Receptors and Insulin Action in Human Myelogenous Leukemia Cell Line K-562. Diabetes 1 April 1985; 34 (4): 347–352. https://doi.org/10.2337/diab.34.4.347
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