Title: G-Proteins
Additional Names: GTP binding proteins
Literature References: Distinct class of membrane associated guanine nucleotide binding proteins characterized by their function as couplers between a wide variety of receptors and their effector molecules in transmembrane signalling pathways. An example is the retinal G-protein, transducin, which links the photon receptor, rhodopsin, q.v., to cGMP phosphodiesterase. G-Proteins are heterotrimeric, with apparent mol wt of 100 kDa and composed of a, b, g subunits. The a subunit contains the guanine nucleotide binding site, possesses GTPase activity, and is specific for each G-protein. b and g subunits form a noncovalent, membrane attached complex. Reviews: A. M. Spiegel, Mol. Cell. Endocrinol. 49, 1-16 (1987); idem, Annu. Rep. Med. Chem. 23, 235-242 (1988); P. J. Casey, A. G. Gilman, J. Biol. Chem. 263, 2577-2580 (1988); H. R. Bourne, Nature 337, 504-505 (1989); L. Birnbaumer, Annu. Rev. Pharmacol. Toxicol. 30, 675-705 (1990); M. E. Linder, A. G. Gilman, Sci. Am. 267, 56-65 (July, 1992). Review of role in disease: A. C. Dolphin, Trends Neurosci. 10, 53-57 (1987). |