Characterization and physiological function of RGEF-1b, a calcium and diacylglycerol-regulated guanine nucleotide exchange factor

Abstract

RasGRPs catalyze exchange of GTP for GDP on p21 Ras and Rap1 proteins. Conserved C1 and EF hand domains in RasGRP polypeptides suggest catalytic activity may be controlled by diacylglycerol (DAG) and Ca2+, respectively. RasGRPs are expressed in platelets, B, T and mast cells and neurons. Functions have been assigned to RasGRPs in blood cells, but their roles in neurons are unknown.;I investigated regulation, functions and effectors of RGEF-1b (a RasGRP homolog) in C. elegans neurons. A single gene rgef-1, encodes RGEF and RGEF-1b via alternative splicing. The rgef-1 promoter is active in all neurons and >95% of gene transcripts encode RGEF-1b (620 amino acids). RGEF-1 deficient animals have impaired chemotaxis to odorants detected by AWC (2-butanone, benzaldehyde). An rgef-1