Mannan-binding lectin-associated serine protease complex (MASP complex)

The Mannan-binding lectin-associated serine protease (MASP) complex is a multi-protein assembly that serves as the primary initiator of the lectin pathway of the complement system (Garred et al., 2016, PMID: 26773144). The complex consists of pattern recognition molecules, such as mannan-binding lectin (MBL) or ficolins, which are physically associated with three serine proteases: MASP-1, MASP-2, and MASP-3 (UniProt O00187, P48740). Upon binding to specific carbohydrate patterns on the surface of pathogens or damaged host cells, MASP-2 is activated and cleaves complement components C4 and C2 to form the C3 convertase, leading to opsonization and inflammation (Heja et al., 2012, PMID: 22891288). Dysregulation or overactivation of this complex is a key driver in the pathogenesis of various inflammatory and microvascular diseases, including IgA nephropathy and hematopoietic stem cell transplant-associated thrombotic microangiopathy (Dobo et al., 2014, PMID: 24933957). Therapeutic intervention typically involves monoclonal antibodies, such as narsoplimab, which target MASP-2 to selectively inhibit the lectin pathway while preserving the classical and alternative pathways for host defense (Omeros Corporation, 2023).

Other names

MBL-MASP complexLectin pathway activation complexMannose-binding lectin-associated serine protease complexFicolin-MASP complex

Inhibition of the enzymatic activity of MASP-2 or MASP-3 within the complex to prevent the cleavage of C4 and C2 or the activation of the alternative pathway, thereby halting the complement cascade.