Conformational Analysis of Phosphatidylglucoside

Abstract

Nagatsuka and her coworkers found a new type of glycolipid in the membrane. They isolated the lipid from human cord RBCs and identified it as phosphatidylglucoside (PhGlc). Furthermore, they analyzed the roles of PhGlc and showed that the PhGlc-based microdomain is involved in GL-7 signaling. Their experiments suggest that PhGlc constitutes a previously undescribed lipid signaling domain involved in cellular differentiation of HL 60 cells. However, it is not clear the reason why PhGlcs form functional microdoomains. We expected that the glucose residue of PhGlc is critical for organization of the carbohydrate-dependent signaling domain involved in cellular differentiation. In this study, geometries of the sugar part were focused on and were optimized systematically by semi-empirical PM3 and ab initio RHF MO methods. We further examined stable conformations of the sugar part. It was found that polar hydroxyl groups in the sugar parts faced to the lateral direction in some of the most stable conformers. It suggests that the glucose residue of PhGlc is important in formation of functional lipid domains by hydrogen bonding to glucoses in the neighboring PhGlc.