[Involvement of G protein in receptor-effector coupling].

G proteins consist of three subunits, alpha, beta and gamma, and bind with GTP or GDP to mediate the transformation and amplification of the signals between receptor on the cell membrane and the intracellular effector system (enzymes or ion channels), which produces various types of messenger. Bacterial toxins such as cholera and pertussis are widely used for research of signal transduction, owing to their ability for ADP-ribosylation of some types of G proteins to modify their functions. Network of signal transduction involving G proteins expands in cells of various organs, and relationship between G protein and receptors, or effectors, has been revealed day by day. Recent information of them are reviewed here.