title: Renal sugar transport in the winter flounder. III. Two glucose transport systems.
abstract: Teased renal tubules of the winter flounder (Pseudopleuronectes americanus) were employed to investigate the structural requirements for two pathways of D-glucose transport which take place preponderantly across the basal (antiluminal) face of renal cells. 1) An inhibition analysis of the equilibrating, Na-independent and phlorizin-sensitive transport of the nonmetabolizable methyl-alpha-D-glucoside (0.1 and 0.5 mM), with 20 glucose analogs (5 mM), was employed to establish the structural requirements for the substrate-carrier interaction: a (pyranose) ring, oxygen, or F at C1, C2-OH, C3-OH, and C4-OH (all axial, 1C model). Some interaction may also occur at C6-OH. D-Glucose shares this transport system. Hydrogen bonding between the oxygens and the carrier is suggested. 2) The phloretin- and phlorizin-sensitive, ouabain-insensitive transport of D-glucose, 2-deoxy-D-glucose, and D-mannose is associated with considerable phosphorylation. The three sugars mutually compete for a shared transport site. The specificity pattern characterizing the transport system defines the following structural requirements: a (pyranose) ring, a free C1-OH, C3-OH, and C4-OH (both axial) and possibly C6-OH. Hydrogen bonding between the carrier and the oxygens at C3, C4, and C6, and covalent bonding at C1 is suggested.
mesh_terms: D000818:Animals; D001692:Biological Transport; D055598:Chemical Phenomena; D002621:Chemistry; D003847:Deoxyglucose / Q000378:metabolism; D005399:Fishes / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism*; D008358:Mannose / Q000031:analogs & derivatives / Q000378:metabolism; D008757:Methylglucosides / Q000378:metabolism; D010693:Phloretin / Q000494:pharmacology; D010695:Phlorhizin / Q000494:pharmacology; D014994:Xylose / Q000494:pharmacology
chemical_list: D008757:Methylglucosides; D003847:Deoxyglucose; D014994:Xylose; D010695:Phlorhizin; D005947:Glucose; D008358:Mannose; D010693:Phloretin