MASP-1

MASP-1 (mannose-binding lectin-associated serine protease 1, encoded by MASP1) is one of two proteases that associate with mannose-binding lectin complexes in plasma. Produced as a zymogen, MASP-1 is the most abundant lectin-pathway protease and acts first in the activation cascade: upon MBL binding to microbial carbohydrates, MASP-1 autoactivates and then transactivates MASP-2, while it can also directly cleave C2 and, to a limited extent, C3. Beyond complement, MASP-1 contributes to coagulation through factor XIII and thrombin-activatable fibrinolysis inhibitor cleavage, and MASP-1/3 isoforms from the same gene are essential for alternative pathway priming. MASP-1 inhibitors are being explored for ischemia-reperfusion and inflammatory conditions.