Background of the antigen
Serine protease inhibitor which exhibits anti-trypsin activity (PubMed:3202973, PubMed:3597401). In the pancreas, protects against trypsin-catalyzed premature activation of zymogens (By similarity). In the male reproductive tract, binds to sperm heads where it modulates sperm capacitance by inhibiting calcium uptake and nitrogen oxide (NO) production (By similarity).