A NOVEL TYPE OF BINDING-SPECIFICITY TO PHOSPHOLIPIDS FOR RAT MANNOSE-BINDING PROTEINS ISOLATED FROM SERUM AND LIVER

Mannose-binding protein (MBP) belongs to the collectin subgroup of C-t ype lectins with specificity for mannose and N-acetylglucosamine sugar s. We investigated whether rat MBPs isolated from serum (S-MBP) and li ver (L-MBP) interact with phospholipids using antibody against each MB P, Both S- and L-MBPs bound to phosphatidylinositol coated onto microt iter wells in a concentration- and a Ca2+-dependent manner. L-MBP also bound to phosphatidylglycerol and weakly to phosphatidylserine. MBPs interacted with liposomes composed of these lipids, S-and L-MBPs bound to phosphatidylinositol 4-monophosphate. L-MBP also bound to cardioli pin. These results provide evidence for a novel type of ligand binding specificity for MBPs, and raise the possibility that phospholipids ar e ligands for collectins. (C) 1997 Federation of European Biochemical Societies.