An Introduction to Cytokine Receptors

Abstract It is well-established that polypeptide hormones elicit their biological effects by binding to receptors expressed on the surface of responsive cells. The characterization of cell surface receptors has proceeded in two distinct phases. Initially, the majority of receptors were described on the basis of their ability to bind radiolabelled derivatives of a particular hormone. These studies allowed the specificity of receptors to be determined and the equilibrium and kinetic characteristics of binding to be investigated. In some cases, through the additional use of chemical cross-linking reagents, an estimate of the apparent molecular weight of receptors was also possible. In general, however, the low abundance of receptors and their integral membrane location hindered their detailed biochemical characterization. Only with the advent and application of appropriate molecular genetic techniques has the predicted primary structure of many receptors been determined. The aim of the following review is to summarize the important structural features that unite receptors of a given family and to highlight themes common to the function of receptors from different families.