(a–c) Sugar headgroup recognition centers of fungal HET-C2, human GLTP, and human FAPP2–GLTPH showing surface electrostatics. Red and blue indicate negative and positive charge, respectively. In the bound glycolipid ligands (green), oxygen atoms are red. (d) Glycolipid transfer selectivity of fungal HET-C2, human FAPP2–C212, and human GLTP determined by intervesicular transfer of radiolabeled glycolipids as previously described (Brown et al. 1985, 1990)