MASP1

[Isoform MASP-1]: Serine protease that activates the lectin pathway of the complement system, a cascade of proteins that leads to phagocytosis and breakdown of pathogens and signaling that strengthens the adaptive immune system. The lectin complement system is activated following association of lectins, such as MBL2, FCN1, FCN2 or FCN3, to carbohydrates on the pathogen surface. Following autoproteolytic processing in response to lectin-binding to pathogen carbohydrates, catalyzes cleavage and activation of MASP2, the next component of the lectin complement pathway..

[Isoform MASP-3]: Serine protease that activates the alternative pathway of the complement system, a cascade of proteins that leads to phagocytosis and breakdown of pathogens and signaling that strengthens the adaptive immune system. The alternative complement pathway acts as an amplification loop that enhances other complement pathways. Isoform MASP-3 specifically catalyzes cleavage and activation of factor D (CFD), the protease that initiates the alternative complement pathway..