title: Glucose-6-phosphate transporter and receptor functions of the glucose 6-phosphatase system analyzed from a consensus defined by multiple alignments.
abstract: The cDNA encoding the protein (P46) that is mutated in glycogen storage disease type-1b (GSD-1b) has been previously cloned by homology with bacterial sequences of the uhp (upper hexose phosphate) system. Hydropathic profiles, transmembrane-prediction analysis, and a multiple alignment of 14 sequences related to P46 (with percentage of identity around 30%) allowed to identify two large domains in the proteins linked by a large variable loop. Highly conserved transmembrane (TM) segments, TM1 and TM4 in the first domain and TM5 in the second one, were identified almost in all the integral proteins related to P46. The multiple alignment allowed definition of a consensus involving the 14 sequences related to P46. The detailed comparison of the consensus with the UhpT (the bacterial G6P transporter) and with UhpC (the bacterial G6P receptor) sequences reveals that the P46 protein could carry both G6P receptor and transporter functions.
authors.affiliation: Laboratoire d'Endocrinologie Métabolique, Departments of Nutrition and Biochemistry, Groupe de Recherche en Transport Membranaire, Centre de Recherche du CHUM, Université de Montréal, Montréal, Québec, Canada. mechinm@hotmail.com
authors.forename: M C
authors.initials: MC
authors.lastname: Méchin
authors.forename: G
authors.initials: G
authors.lastname: van de Werve
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D017920:Antiporters; D001426:Bacterial Proteins / Q000737:chemistry*; D002352:Carrier Proteins / Q000737:chemistry*; D016384:Consensus Sequence; D029968:Escherichia coli Proteins; D005952:Glucose-6-Phosphatase / Q000737:chemistry*; D019298:Glucose-6-Phosphate / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry*; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins; D009154:Mutation; D010770:Phosphotransferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D017920:Antiporters; D001426:Bacterial Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D007527:Isoenzymes; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D009004:Monosaccharide Transport Proteins; C503531:SLC37A4 protein, human; C063498:UhpT protein, E coli; C111261:glucose 6-phosphate(transporter); C490131:uhpC protein, E coli; C086587:uhpC protein, bacteria; D019298:Glucose-6-Phosphate; D010770:Phosphotransferases; D005952:Glucose-6-Phosphatase