Proteolytic activities of two types of mannose-binding lectin-associated serine protease.
Mannose (or mannan)-binding lectin (MBL) is an oligomeric serum lectin that plays a role in innate immunity by activating the complement system. In human, two types of MBL-associated serine protease (MASP-1 and MASP-2) and a truncated protein of MASP-2 (small MBL-associated protein; sMAP or MAp19) are complexed with MBL. To ... clarify the proteolytic activities of MASP-1 and MASP-2 against C4, C2, and C3, we isolated these two types of MASP in activated forms from human serum by sequential affinity chromatography. On an anti-MASP-1 column, MASP-2 passed through the column in the presence of EDTA and high salt concentration, whereas MASP-1 was retained. Isolated MASP-1 and MASP-2 exhibited proteolytic activities against C3 and C4, respectively. C2 was activated by both MASPs. C1 inhibitor (C1 INH), an inhibitor for C1r and C1s, formed equimolar complexes with MASP-1 and MASP-2 and inhibited their proteolytic activities.
Mesh Terms:
Binding, Competitive, Carrier Proteins, Collectins, Complement Activation, Complement C1 Inactivator Proteins, Dose-Response Relationship, Immunologic, Enzyme Activation, Humans, Hydrolysis, Lectins, Mannose, Mannose-Binding Protein-Associated Serine Proteases, Serine Endopeptidases, Serine Proteinase Inhibitors
Binding, Competitive, Carrier Proteins, Collectins, Complement Activation, Complement C1 Inactivator Proteins, Dose-Response Relationship, Immunologic, Enzyme Activation, Humans, Hydrolysis, Lectins, Mannose, Mannose-Binding Protein-Associated Serine Proteases, Serine Endopeptidases, Serine Proteinase Inhibitors
J. Immunol.
Date: Sep. 01, 2000
PubMed ID: 10946292
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