Rabbit polyclonal antibody to Rabphilin~3A (P231)

The carboxy~terminal of rabphilin~3A consists of two C2 domains, A and B,and the amino~terminal (residues 45~170) contains a cysteine~rich rich region with two zinc finger motifs. Rabphilin~3A belongs to a family of other carboxyterminal type (C~type) tandem C2 proteins, which includes synaptotagmins and Doc2. Rabphilin is expressed in neuroendocrine cells and co~localizes with Rab3A on synaptic vesicles and chromaffin granules. Rabphilin~3A binds Rab3a/GTP/Mg+ within amino~terminal residues 45 and 170. Rabphilin~3A binds calcium ions and phosphatidylinositol 4,5~bisphophate containing lipid vesicles within its C2 domains. Rabphilin~3A is a positive regulator of calcium dependent exocytosis, while Rab3a is a negative regulator of exocytosis. Although rabphilin~3A associates with Rab3a, they seem to influence exocytosis independently of each other. Rabphilin~3A effects are likely mediated through interactions with an unknown factor that recognizes the Rab3 binding domain.