CAST into the synapse

For the nervous system to function properly, neurotransmitters must be released in a regulated fashion from an active zone in the presynaptic membrane, but relatively little is known about how synaptic vesicles are directed to this zone in the first place. On page 577, Ohtsuka et al. characterize a novel protein associated with the active zone.

The cytomatrix at the active zone (CAZ) is believed to be important in determining synaptic vesicle localization. In the new work, the authors began with traditional biochemistry, comparing crude membrane and postsynaptic density fractions from rat brain to identify proteins associated with the synapse. One novel protein was found and named CAZ-associated structural protein (CAST). Electron microscopy places CAST at the CAZ in conventional synapses. CAST associates with two known CAZ proteins, RIM1 and Munc13–1,...