Role of Sulfhydryl Groups in Functioning of Adenylyl Cyclase Signaling System

This review considers the literature data and author's own results on the role of SH-groups in functioning of the hormone-sensitive adenylyl cyclase system (ACS). It has been shown that the state of SH-groups affects crucially all main stages of the hormonal signal transudation: the ligand-binding properties of receptor and its coupling to G-proteins, interaction of G-proteins with adenylyl cyclase (AC) and its catalytic activity. It is noted that for the receptors, coupled to AC by a stimulating mode, the central aspect of the SH-dependent regulation of ACS is shifted to the receptor, while for the receptors coupled to AC by an inhibiting mode, it coincides with G-protein of the inhibiting type, which is sensitive to the SH-group state. Based on the performed comparative analysis of primary structures of signalling proteins—ACS components and of literature data, there are revealed the cysteine residues determining the functional activity of these proteins in the process of the hormonal signal transudation. The conclusion is made that the SH-group state (the ratio of free SH-groups and disulfide bonds) is the main factor determining the ACS reactivity to hormonal effects and selectivity of process of the signal transudation.