Receptors for insulin and growth hormone on lymphoid cells

This chapter describes the techniques in which the cultured human lymphocyte has been used not only to measure insulin and human growth hormone in radioreceptor assays but also to define properties of their respective receptors. These include (1) the binding characteristics of the insulin and growth hormone receptor, (2) the transformation of freshly isolated lymphocytes from blood to permanent cultured lines by Epstein-Barr virus (EBV) transformation, (3) the structural features of both the insulin and growth hormone receptor, and (4) the ability of the insulin receptor to serve as a tyrosine-specific protein kinase. For the assay of complex solutions in which the hormone represents only a small fraction of the material or is in the presence of interfering substances a gel filtration step is required prior to testing in RRA. For the insulin RRA there are at least three advantages to these procedures: (1) interfering substances may be removed, (2) proinsulin- related materials can be separated from insulin, as well as the insulinlike growth factors, (3) lyophilization can be used as a concentrating step.