Insulin Binding and Glucose Transport

Abstract

This chapter discusses the insulin binding and glucose transport. The insulin binding is explained with the help of recent data on cellular localization, cooperativity, regulation of receptors and receptors in normal and transformed cells. The action of insulin starts with the binding of the hormone to specific receptors on the plasma membrane of target cells. Studies of insulin receptors require a satisfactory reagent probe, one with the same biological properties as the native insulin. The monoiodinated insulin has a biological activity similar to native insulin, based on stimulation of glucose oxidation by fat cells. For glucose transport, the chapter reviews various regulatory aspects, such as cell growth, adaptation, and hormonal influences in normal and neoplastic cells. The chapter focuses on the mechanism and regulation of glucose transport in cells where glucose is transported by facilitated diffusion. This process is mediated by a specific glucose carrier but does not require energy; therefore, the direction of glucose flux is in accordance with its concentration gradient. The most common experimental design for measuring rates of substrate transport is the zero-trans influx procedure.