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Stichodactyla helianthus Kunitz inhibitor protein ShPI-1, Heteractis crispa protease inhibitor stichotoxin-Hcr2e, and similar proteins This model includes Kunitz inhibitor protein ShPI-1, the major protease inhibitor from the sea anemone Stichodactyla helianthus, as well as protease inhibitor stichotoxin-Hcr2e (also called PI- stichotoxin-Hcr2e, PI-SHTX-Hcr2e, or Kunitz-type serine protease inhibitor InhVJ) and HCRG1 from Heteractis crispa. ShPI-1 has an unusually broad specificity toward several serine proteases, including trypsin, chymotrypsin, human neutrophil elastase, kallikrein and plasmin, and can also bind aspartic and cysteine proteases, such as pepsin and papain, respectively. PI-SHTX-Hcr2e and HCRG1 inhibit trypsin and chymotrypsin, but do not inhibit the serine proteases plasmin, thrombin, kallikrein, the cysteine proteinase papain, and the aspartic protease pepsin. The structures of these domains are similar to those of Kunitz-type proteinase inhibitors such as BPTI (bovine pancreatic trypsin inhibitor), showing an alpha/beta fold with irregular secondary structure stabilized by three disulfide bonds. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",