Double C2 domain protein B (DOC2B) enhances exocytosis in chromaffin cells, pancreatic β-cells and adipocytes. Here, the authors showed that it also mediates spontaneous vesicle release from

mouse hippocampal and cerebellar neurons. DOC2B is structurally and biochemically similar to synaptotagmin 1, which also contains two cytoplasmic C2 domains, and competes with synaptotagmin

1 for SNARE (soluble N-ethylmaleimide-sensitive factor attachment receptor) complex binding. These findings highlight the membrane curvature-inducing action of multiple C2 domain proteins

in neurotransmitter release.