MASP1 (protein)

Mannan-binding lectin serine protease 1 also known as mannose-associated serine protease 1 (MASP-1) is an is_associated_with::enzyme that in humans is encoded by the MASP1 is_associated_with::gene.

MASP-1 is involved in the lectin pathway of the is_associated_with::complement system and is responsible for cleaving C4 and C2 to form C4b2b, a is_associated_with::C3-convertase.

Function
MASP-1 is a is_associated_with::serine protease that functions as a component of the is_associated_with::lectin pathway of complement activation. The complement pathway plays an essential role in the innate and adaptive immune response. MASP-1 is synthesized as a is_associated_with::zymogen and is activated when it complexes with the pathogen recognition molecules of lectin pathway, the mannose-binding lectin and the ficolins. This protein is not directly involved in complement activation but may play a role as an amplifier of complement activation by cleaving complement C2 or by activating another complement serine protease, MASP-2. MASP-1 is also able to cleave fibrinogen and factor XIII and may be involved in coagulation. A splice variant of this gene which lacks the serine protease domain functions as an inhibitor of the complement pathway.