Mannan-binding lectin-associated serine protease (MASP) and MAp19 (MASP/MAp19)

Mannan-binding lectin-associated serine proteases (MASPs) and the non-enzymatic protein MAp19 (also known as sMAP) are essential components of the lectin pathway of the complement system (UniProt O00187, P48740). MASP-1 and MASP-2 are the primary enzymatic drivers; upon binding of pattern recognition molecules like MBL or ficolins to pathogen surfaces, MASP-2 cleaves complement components C4 and C2 to initiate the complement cascade (PubMed: 22235284). MAp19 is a truncated splice variant of the MASP2 gene that lacks the catalytic domain and is thought to play a regulatory role in the assembly of the MBL-MASP complex (PubMed: 10438934). Dysregulation of the lectin pathway is implicated in various inflammatory and autoimmune conditions, including IgA nephropathy, thrombotic microangiopathies, and ischemia-reperfusion injury (PubMed: 32690543). Therapeutic targeting, particularly of MASP-2 by drugs like narsoplimab, aims to inhibit pathological complement activation while preserving the classical and alternative pathways (Omeros Corporation, 2023).

Other names

MASPsMBL-associated serine proteasessMAPSmall MBL-associated proteinMannose-binding lectin-associated serine proteaseMAp19

Inhibition of MASP-2 enzymatic activity to prevent the formation of C3 convertase via the lectin pathway (PubMed: 22235284).