The importance of G-protein beta lambda subunits.

As the properties of more and more isoforms of the molecules involved in G-protein-mediated signal transduction pathways are unravelled, surprising diversity and versatility are being revealed. The path from receptor to effector is not dictated exclusively by the alpha subunits of heterotrimetric G proteins. The nature of the beta lambda subunit complex probably controls interactions of G(alpha) with receptors. In addition, dissociation of G(alpha)-GTP from G(beta lambda)provides two signalling complexes, and these proteins regulate effectors independently or synergistically. Synergistic or conditional regulation of effectors by G(alpha) and G(beta lambda)can provide a molecular signal that records the association of independent events.