A NEW MODEL FOR THE MEMBRANE TOPOLOGY OF GLUCOSE-6-PHOSPHATASE - THE ENZYME INVOLVED IN VON-GIERKE-DISEASE

Very recently we have proposed [Hemrika et al. (1997) Proc. Natl. Acad . Sci. USA 94, 2145-2149] that the active site of the vanadate-contain ing chloroperoxidase from the fungus Curvularia inaequalis, of which t he tertiary structure is known, is structurally very similar to that o f the membrane-bound mammalian glucose-6-phosphatases for which no str uctural data are available. The proposed active site of glucose-6-phos phatase, however, is incompatible with the six transmennbrane-helix to pology model that is currently used. Here we present a new topology mo del for glucose-6-phosphatase which is in agreement with all available data. (C) 1997 Federation of European Biochemical Societies.