Serine protease which has a preference for Arg or Lys in position P1 and uncharged residues in positions P2 and P3. Shows specificity towards FGF2 in vitro. Optimum pH is 8. Expressed specifically in Purkinje neurons of the cerebellum (at protein level). Also detected in spinal cord. Proteolytically cleaved via an autocatalytic mechanism. Belongs to the peptidase S1 family.