title: Homology of the human intestinal Na+/glucose and Escherichia coli Na+/proline cotransporters.
abstract: Cotransport proteins are responsible for the active accumulation of organic substrates in cells. Na+ gradients provide the driving force for uptake of most substrates into eukaryotes and for a few substrates in some prokaryotes. We report here the cloning and sequencing of the human intestinal Na+/glucose cotransporter (SGLT1) and compare its structure with other cloned transporters. At the DNA level and the predicted amino acid and secondary structure levels, close homology is evident between the human and rabbit intestinal Na+/glucose cotransporters, and a significant homology is found between these and the Escherichia coli Na+/proline cotransporter (putP). No homology is detectible with other known proteins. We infer from these results that the mammalian Na+/glucose and prokaryote Na+/proline cotransporters share a common ancestral gene.
authors.affiliation: Department of Physiology, University of California, Los Angeles School of Medicine 90024-1751.
authors.forename: M A
authors.initials: MA
authors.lastname: Hediger
authors.forename: E
authors.initials: E
authors.lastname: Turk
authors.forename: E M
authors.initials: EM
authors.lastname: Wright
mesh_terms: D000595:Amino Acid Sequence; D026921:Amino Acid Transport Systems, Neutral; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005796:Genes; D005798:Genes, Bacterial; D005947:Glucose / Q000378:metabolism; D006801:Humans; D007082:Ileum / Q000378:metabolism*; D008871:Microvilli / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009004:Monosaccharide Transport Proteins / Q000235:genetics*; D011392:Proline / Q000378:metabolism; D011487:Protein Conformation; D011817:Rabbits; D012689:Sequence Homology, Nucleic Acid; D027981:Symporters
chemical_list: D026921:Amino Acid Transport Systems, Neutral; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D009004:Monosaccharide Transport Proteins; D027981:Symporters; C060609:PutP protein, E coli; D011392:Proline; D005947:Glucose