Inhibitor of serine proteases. Its primary target is elastase, but it also has a moderate affinity for plasmin and thrombin. Irreversibly inhibits trypsin, chymotrypsin and plasminogen activator. The aberrant form inhibits insulin-induced NO synthesis in platelets, decreases coagulation time and has proteolytic activity against insulin and plasmin.
Reversible chymotrypsin inhibitor. It also inhibits elastase, but not trypsin. Its major physiological function is the protection of the lower respiratory tract against proteolytic destruction by human leukocyte elastase (HLE).
Subcellular locations: Secreted, Endoplasmic reticulum
The S and Z allele are not secreted effectively and accumulate intracellularly in the endoplasmic reticulum.
Subcellular locations: Secreted, Extracellular space, Extracellular matrix
Ubiquitous. Expressed in leukocytes and plasma.