Proteinase 3

Proteinase 3 (also known as PR3, Myeloblastin, or c-ANCA) is a type of enzyme that is encoded by the PRTN3 gene in humans. It is primarily found in neutrophil granulocytes, a type of white blood cell that plays a crucial role in the immune system.

Structure

Proteinase 3 is a serine protease that is approximately 29 kDa in size. It is composed of a single chain of 222 amino acids. The structure of Proteinase 3 includes two disulfide bonds and a catalytic triad of histidine, aspartate, and serine residues.

Function

Proteinase 3 is involved in a variety of biological processes. It is capable of degrading a number of proteins, including elastin, collagen, and fibronectin. This makes it important in tissue remodeling and the inflammatory response. Proteinase 3 is also involved in the processing of cytokines, which are signaling molecules that mediate and regulate immunity, inflammation, and hematopoiesis.

Clinical significance

Proteinase 3 is the target of anti-neutrophil cytoplasmic antibodies (ANCAs) in a form of vasculitis known as granulomatosis with polyangiitis (GPA). These antibodies can lead to the activation of neutrophils, causing them to attack the blood vessels and lead to inflammation and damage.

See also

• Neutrophil granulocytes
• Vasculitis
• Granulomatosis with polyangiitis