YWK-II protein/APLP2 is a member of an evolutionarily conserved APP family that includes amyloid precursor protein （APP） and amyloid precursor-like protein-1 （APLP1）. YWK-II/APLP2 functions as a novel G（0）-protein-coupled receptor for Müllerian inhibiting substance （MIS） in cell survival. Human leukocyte antigen-B-associated transcript 3 （Bat3）, an important regulator involved in apoptosis, can interact with YWK-II/APLP2 and enhance its stability by reducing its ubiquitylation and degradation by the ubiquitin-proteasome system. May play a role in the regulation of hemostasis. The soluble form may have inhibitory properties towards coagulation factors. May interact with cellular G-protein signaling pathways. Inhibits trypsin, chymotrypsin, plasmin, factor XIA and plasma and glandular kallikrein.