Neurotrypsin: Proteins and Enzymes

Neurotrypsin is a central nervous system-expressed serine protease whose truncation or absence causes nonsyndromic mental retardation. It is most prominently expressed in structures that are involved in the processing and storage of learned behavior and memory, such as 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. There are three sequences published for neurotrypsin to date; 875, 834 and 505 amino acids in length. The predicted masses are 97, 92.5 and 55.7 kDa respectively, with predicted pI of 9.14, 8.88 and 6.57. The three forms all start at the same place. The 505 residue form terminates in the last SRCR domain, before the catalytic domain, and the 834 amino acid form has a 40 amino acid deletion that starts just after the PC site, and includes the catalytic histidine, thus both species would be proteolytically inactive.