Cell-membrane hormone receptors: some perspectives on their structure and function relationship

Abstract

There are three structural regions common to hormone receptors on the cell membrane: an external region containing the ligand-specific binding domain, a hydrophobic region transversing the membrane, and a cytoplasmic region involved in the expression of activity. The structural features of these regions are broadly reviewed in regard to their functional roles. It is suggested that the specificity of cellular response to hormonal stimulation lies not only in the binding of a specific ligand by the external domain but also in the cytoplasmic region of a receptor. The cytoplasmic region can either interact specifically with a regulatory system or express its own specific ligand-dependent catalytic activity. The fundamental question of how ligand binding can lead to the expression and regulation of receptor activity is considered.