The Regulating Function of Heterotrimeric G Proteins in the Immune System

Heterotrimeric guanine nucleotide-binding proteins (G proteins), which consist of an alpha-, a beta- and a gamma-subunit, have crucial roles as molecular switches in the regulation of the downstream effector molecules of multiple G protein-coupled receptor signalling pathways, such as phospholipase C and adenylyl cyclase. According to the structural and functional similarities of their alpha-subunits, G proteins can be divided into four subfamilies: G alpha s, G alpha i/o, G alpha q/11 and G alpha 12/13. Most of the alpha- and the beta gamma-subunits are abundantly expressed on the surface of immune cells. Recent studies have demonstrated that G proteins are a group of important immunomodulatory factors that regulate the migration, activation, survival, proliferation, differentiation and cytokine secretion of immune cells. In this review, we summarise the recent findings on the functions of G proteins in immune regulation and autoimmunity.