MASP-2

MASP-2 (mannose-binding lectin-associated serine protease 2) is the key enzymatic effector of the lectin complement pathway, encoded by the MASP2 gene. When mannose-binding lectin or ficolins engage microbial surfaces, MASP-2, activated through autoactivation and transactivation by MASP-1, cleaves C4 and C2 to assemble the C3 convertase C4b2a. Unlike MASP-1, MASP-2 is largely dedicated to complement and circulates bound to its pattern-recognition partners in a proenzyme state. Hereditary MASP2 deficiency, while rare, causes a profound lectin-pathway defect that manifests as recurrent infections, particularly in early childhood; polymorphisms in MASP2 have also been linked to various inflammatory and thrombotic disorders, prompting development of targeted MASP-2 inhibitors.