Predicted to enable serine-type endopeptidase inhibitor activity. Involved in imaginal disc-derived wing expansion; negative regulation of innate immune response; and negative regulation of protein metabolic process. Located in extracellular region. Is expressed in several structures, including adult head; embryonic anal pad; female germline cell; gut section; and primary tracheal branch. Human ortholog(s) of this gene implicated in intermediate coronary syndrome; neurodegenerative disease (multiple); thrombophilia (multiple); thrombosis; and toxic shock syndrome. Orthologous to several human genes including SERPINA12 (serpin family A member 12); SERPINB1 (serpin family B member 1); and SERPINC1 (serpin family C member 1).