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  • MASP-3 and its association with distinct complexes of the mannan-binding lectin complement activation pathway.

MASP-3 and its association with distinct complexes of the mannan-binding lectin complement activation pathway.

Immunity (2001-08-04)
M R Dahl, S Thiel, M Matsushita, T Fujita, A C Willis, T Christensen, T Vorup-Jensen, J C Jensenius
要旨

The mannan-binding lectin (MBL) pathway of complement activation is part of the innate immune defense. The binding of MBL to microbial carbohydrates activates the MBL-associated serine proteases (MASPs), which recruit the complement factors, C4 and C2, to generate the C3 convertase or directly activate C3. We present a phylogenetically highly conserved member of the MBL complex, MASP-3, which is generated through alternative splicing of the MASP-1/3 gene. The designation of MASP-3 as a protease is based on homology to known MASPs. Different MBL oligomers were found to have distinct MASP composition and biological activities. MASP-1, MAp19, and direct C3-cleaving activity are associated with smaller oligomers whereas MASP-3 is found together with MASP-2 on larger oligomers. MASP-3 downregulate the C4 and C2 cleaving activity of MASP-2.