ABSTRACT
MASP3 is one of the mannan-binding lectin-associated serine proteases(MASPs)of the complement lectin pathway.It is the alternative splice product of MASP1/3 gene.MASP3 does not participate in the activation of the lectin pathway and it has no cleavage activity towards C2,C4 and C3.Recently,a novel MASP3 function has been discovered that it may play an important role in the alternative pathway through direct activation of factor D.Besides,studies on the murine disease model suggested that MASP3 might be a new therapeutic target for the treatment of alternative pathway-mediated diseases.This review present an overall description of the coding gene and protein structure of MASP3 protein and provide recent research progress on its function and especially in its role in the alternative pathway-mediated diseases.