[Participation of adenylate cyclase in conducting hormonal signals through membranes]

Abstract

Mechanisms are considered which conduct and amplify a hormonal signal with participation of adenylate cyclase. It is shown that cell sensitivity to hormone is governed by the constant of receptor affinity for hormone, by the content of receptors in the membrane as well as of the degree of receptors conjugation with the enzyme. Mechanisms regulating the amount of receptors in the membrane, the role of guanylic and other purine nucleotides in their functioning are discussed. Properties of GTR-dependent proteins realizing the functional conjugation of receptors with adenylate cyclase and models of adenylate cyclase complex molecular organization and functioning in the membrane are discussed. The complex of catalytic subunit with GTP-dependent protein is a choloenzyme of adenylate cyclase. An assumption is made that not only GTP but also GDP may influence the formation of this complex. The adenylate cyclase activity is regulated by variations in the equilibrium between apo- and choloenzyme, different agents changing this equilibrium, affecting either protein-protein of protein-nucleotide interaction. The presence of several GTP-dependent centres is supposed to be in the adenylate cyclase complex, in one of which GDP may be transformed to GTP due to the phosphotranspherase reaction.