Gab1

Abstract

G alpha o 1893G regulators of the Gao protein may provide a cellspecific mechanism for Gao-regulated signaling pathways. PTX catalyzes the ADP-ribosylation of the a subunits of the Go, Gi, and Gt proteins at the C-terminal cysteine residue (À4 position). This prevents the G protein from interacting with GPCRs on the cell membrane, thus interfering with intracellular signaling. 1896 G alpha o G alpha o 1897 G cyclase, guanylate cyclase, Rap1 GTPaseactivating protein (Rap1GAP), axin, and pins. Compartmentalization of these signaling molecules in membrane rafts may ensure specificity and fidelity in Gao signaling. Go is the most abundant G protein in the central nervous system, where it comprises about 1% of membrane proteins in the mammalian brain. Go regulates neuronal development, memory, visual reception, olfactory reception, and taste reception. It is also localized in heart tissue and implicated in heart contractility. Its expression is regulated during the development of the brain and heart. Somatic mutations in the GNAO1 gene induce human cancers by rendering Gao constitutively activated. Heterozygous mutations in the GNAO1 gene cause epileptic encephalopathy by destabilizing Gao. Gao-deficient mice have several neurological deficits, including tremors, seizures, hyperalgesia, motor control impairment, and olfactory impairment. Muscarinic regulation of heart rate and heart rate variability is also impaired in Gao-deficient mice. Drosophila melanogaster mutants with loss of function of Gao show impaired morphogenesis of the heart and epithelial polarity of cardiac cells and abnormal sleep. Gao-deficient C. elegans has phenotypes including neuronal migration defects, hyperactive locomotion, and egg laying.