Figure 1.

Structures of proteins required for the fast, Ca²⁺-stimulated release of neurotransmitters. (A) The SNARE complex (Protein Data Bank (PDB) ID , Sutton et al, 1998) and the C2A and C2B domains of synaptotagmin I (PDB IDs , Shao et al, 1998; and , Fernandez et al, 2001, respectively) are required at sites of synaptic vesicle fusion on the presynaptic plasma membrane. (B) Complexin bound to the SNARE complex (PDB ID , Chen et al, 2002). The transmembrane domains and unstructured regions are modelled in the figure. Amino- and carboxy-terminal ends of each protein are indicated. SNAP-25, synaptosome-associated protein of 25kDa; VAMP, vesicle-associated membrane protein.