The synaptic serine protease neurotrypsin is thought to be important for adaptive synaptic processes required for cognitive functions. Truncation or absence of Neurotrypsin causes severe mental retardation.
It is most prominently expressed in the cerebral cortex, the hippocampus, and amygdala. Evidence suggests that neurotrypsin has multiple functions, including axonal outgrowth, maintaining neuronal plasticity, and arranging the perineuronal environment, partly in coordination with other proteases including tissue plasminogen activator.