A family of proteins highly enriched at the active zone; name is related to high content of glutamate (E), leucine (L), lysine (K), and serine (S) residues. Generally recognized as a synaptic scaffolding protein that is known to interact with Bassoon, Piccolo, Liprin-α, RIM, and Rab6 among other proteins. Also known as ERC or CAST proteins.

 Synaptic Proteins and Regulated Exocytosis