<p>This entry represents the zinc-binding domain found in rabphilin Rab3A. The small G protein Rab3A plays an important role in the regulation of neurotransmitter release. The crystal structure of the small G protein Rab3A complexed with the effector domain of rabphilin-3A shows that the effector domain of rabphilin-3A contacts Rab3A in two distinct areas. The first interface involves the Rab3A switch I and switch II regions, which are sensitive to the nucleotide-binding state of Rab3A. The second interface consists of a deep pocket in Rab3A that interacts with a SGAWFF structural element of rabphilin-3A. Sequence and structure analysis, and biochemical data suggest that this pocket, or Rab complementarity-determining region (RabCDR), establishes a specific interaction between each Rab protein and its effectors. It has been suggested that RabCDRs could be major determinants of effector specificity during vesicle trafficking and fusion [<cite idref="PUB00008096"/>].</p> Rabphilin-3A effector, zinc-binding