The mechanisms that allow the nervous system of animals to interpret and respond to their environment requires an astonishing complexity of neuronal connections and signaling pathways. The past decade has seen the emergence of a common theme in the mechanisms mediating these seemingly complex tasks: during evolution, nervous system development has taken components of less complex cells and pathways and modified them to fit the requirements of neuronal signaling. Neurexins were originally identified as a polymorphic family of neuronal-specific type 1 cell surface membrane proteins that were postulated to serve a unique role in specifying synaptic specificity and docking synaptic vesicles at the active zone. However, recent genetic and molecular analyses have provided novel insights that suggest neurexins are evolutionarily conserved and mediate many aspects of cellular function.
Neurexins were first identified by Südhof and colleagues as cell surface receptors for α-latrotoxin (19). This component of black...
