Unc-13 Homolog B (UNC13B)

UNC13B is expressed in the kidney cortical epithelial cells and is upregulated by hyperglycemia. The encoded protein shares a high level of similarity to the rat homolog, and contains 3 C2 domains and a diacylglycerol-binding C1 domain. Hyperglycemia increases the levels of diacylglycerol, which has been shown to induce apoptosis in cells transfected with this gene and thus contribute to the renal cell complications of hyperglycemia. Studies in other species also indicate a role for this protein in the priming step of synaptic vesicle exocytosis. The deduced 1,591-amino acid protein contains an N-terminal 100-residue stretch that is 85% identical to rat Munc13-1, and a highly conserved C-terminal segment that is 93% identical over 1,200 amino acids to rat Munc13-2.