protein kinase C conserved region 1 (C1 domain) found in the Munc13 family
The Munc13 gene family encodes a family of neuron-specific, synaptic molecules that bind to syntaxin, an essential mediator of neurotransmitter release. Munc13-1 is a component of presynaptic active zones in which it acts as an essential synaptic vesicle priming protein. Munc13-2 is essential for normal release probability at hippocampal mossy fiber synapses. Munc13-3 is almost exclusively expressed in the cerebellum. It acts as a tumor suppressor and plays a critical role in the formation of release sites with calcium channel nanodomains. The C1 domain is a cysteine-rich zinc binding domain that does not bind DNA nor possess structural similarity to conventional zinc finger domains; it contains two separate Zn(2+)-binding sites.