Table 2 Summary of proteolytic cleavage sites in SNARE proteins and synaptotagmin Total Number of Protease Cleavage Sites Trypsin Papain Clostripain Protein Number Ave Min Ave Min Ave Min of Isoforms Analyzed Syntaxin 94 42 29 81 53 20 6 SNAP25 25 12 8 25 20 6 5 (N[H.
However, after limited proteolysis of PSA by trypsin, [alpha]-chymotrypsin, clostripain, or V8 protease, the resulting PSA proteolytic fragments were not immunoreactive as evidenced by Western blot analysis under reducing as well as nonreducing conditions (data not shown).