Proteinase-3 is a neutral serine proteinase that belongs to the peptidase S1 family and Elastase subfamily. It contains one peptidase S1 domain and it is expressed mainly in neutrophil granulocytes. The primary function of Proteinase-3 is thought to be degradation of extracellular proteins at sites of inflammation, but excessive or prolonged proteolytic activity may cause harmful effects in the body. It is the epitope of anti-neutrophil cytoplasmic antibodies (ANCAs) of the cANCA (cytoplasmic subtype) class, a type of antibody frequently found in the disease Wegeners granulomatosis.
