This gene encodes a liver vitamin K-dependent glycoprotein that is synthesized in the liver and secreted into the plasma. The encoded protein plays a role in regulating blood coagulation by complexing with protein Z-dependent protease inhibitor to directly inhibit activated factor X at the phospholipid surface. Deficiencies in this protein are associated with an increased risk of ischemic arterial diseases and fetal loss. Mutations in this gene are the cause of protein Z deficiency. Alternate splicing results in multiple transcript variants. [provided by RefSeq, Jan 2012]