RAB3A, Member RAS Oncogene Family (RAB3A)

The RAS gene superfamily is divided into 3 main branches according to protein homology. In mammals the first branch includes the classic RAS genes as well as RAL and RRAS. The RHO genes belong to the second branch and the RAB genes to the third. The RAB genes were so named because they were first isolated from a rat brain library. The predicted 220-amino acid human RAB3A protein shares 99% and 78% identity with rat Rab3A and human RAB3B, respectively.

Synapsin I stimulated the Rab3a cycle by increasing GTP binding, GTPase activity, and Rab3a recruitment to the synaptic vesicle membrane. Conversely, Rab3a inhibited synapsin I binding to actin and synapsin I-induced synaptic vesicle clustering.