The BioGRID | PUBLICATION VIEW

	J. Immunol. Sep (2000); 165(5):2637-42
Proteolytic activities of two types of mannose-binding lectin-associated serine protease.
Matsushita M, Thiel S, Jensenius JC, Terai I, Fujita T
Department of Biochemistry, Fukushima Medical University School of Medicine, Fukushima, Japan. mmatsu@fmu.ac.jp
Abstract: 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.
[PUBMED: 10946292]