Structural and functional roles of the amino-terminal region and collagen-like domain of human serum mannan-binding protein

Abstract

The serum mannan-binding protein (S-MBP) is a Ca2+-dependent C-type animal lectin specific for mannose and N-acetylglucosamine, which plays an important role in first-line host defense. To study the structure and function relationship of the lectin, a full-length human S-MBPcDNA was expressed in Sf9 insect cells using a baculovirus expression system, and a cDNA encoding the carbohydrate recognition domain (CRD) of human S-MBP was expressed in E.coli. The properties of the recombinant S-MBP and recombinant S-MBP-CRD were compared with those of the native human S-MBP and the CRD of the native S-MBP. The results indicated that functional human S-MBP can be successfully expressed in Sf9 cells and functional S-MBP-CRD in E.coli. In addition, the amino-terminal region and collagen-like domain are required for higher oligomer formation and play important roles in complement activation.