A family of proteins (guanine nucleotide exchange factors) involved in the cycle of activation and inactivation that occurs with the small G-proteins such as ras, rap, and rho. The exchange factors stimulate the release of bound GDP, allowing GTP to bind and activate the G protein. Inactivation occurs when the GTP is hydrolysed to GDP, stimulated by GTPase activating proteins (GAPs). Members of the family include cytohesin, ARNO, Gea-1 and 2, kalirin, and yeast Sec7.
Subjects: Medicine and Health.