Role of βγ-Dimers of GTP-Binding Proteins in Processes of Hormonal Signal Transduction

This review summarizes and analyzes data on structural and functional peculiarities of β- and γ-subunits of heterotrimeric G proteins and their participation in βγ-dimer in processes of hormonal signal transduction to the cell. The molecular mechanisms are discussed, which are responsible for formation of the βγ-dimer complex and its interaction with the wide spectrum of signal and structural proteins, such as G protein α-subunit, serpentine type receptors, kinases of G protein-coupled receptors, adenylyl cyclase, phospholipase Cβ2, phosphatidyl-inositol-3-kinase, Raf-kinase, potassium and calcium channels, microtubular and RGS-proteins. The characteristics of β- and γ-subunits are given for living organisms of different phylogenetic levels (lower eukaryotes, fungi, plants, vertebrates, and invertebrates). It is concluded that the βγ-dimer is the most important regulatory link in various signal systems to carry out switch from one signal cascade to another and thereby to determine the final cellular response to the signal impulse.