Which protein senses the calcium, and which three proteins zip the vesicle onto the membrane? · Lobeworks/17

Synaptotagmin senses the calcium; the SNAREs zip.

Which protein senses the calcium, and which three proteins zip the vesicle onto the membrane?

Synaptotagmin senses the calcium; the SNAREs zip. Synaptotagmin-1 sits on the vesicle and needs several calcium ions bound before it acts, which makes release steep and fast. The SNARE complex is synaptobrevin (VAMP2) on the vesicle with syntaxin-1 and SNAP-25 on the terminal membrane: their helices wind into a bundle that holds the vesicle primed, and synaptotagmin's push completes the fusion.