The Yin and Yang of synaptic active zone assembly

Mechanisms of synapse assembly are relevant for our understanding of neuronal development, as well as the processes of learning and memory. The presynaptic active zone membrane is covered by a protein-rich matrix, which is thought to be important for fast vesicle fusion, as well as potentially contributing to synapse stability. By genetic analysis, matrix proteins of active zones from various families have been shown to promote synapse assembly. New evidence shows that the evolutionarily conserved protein RSY-1 (regulator of synaptogenesis 1) locally inhibits active zone assembly to restrict synapse formation to the correct positions during Caenorhabditis elegans development. Thus, the protein interactions that assemble the architecture of the active zone appear to locally integrate not only positive but also negative signals.