title: Role of monosaccharide transport proteins in carbohydrate assimilation, distribution, metabolism, and homeostasis.
abstract: The facilitated diffusion of glucose, galactose, fructose, urate, myoinositol, and dehydroascorbicacid in mammals is catalyzed by a family of 14 monosaccharide transport proteins called GLUTs. These transporters may be divided into three classes according to sequence similarity and function/substrate specificity. GLUT1 appears to be highly expressed in glycolytically active cells and has been coopted in vitamin C auxotrophs to maintain the redox state of the blood through transport of dehydroascorbate. Several GLUTs are definitive glucose/galactose transporters, GLUT2 and GLUT5 are physiologically important fructose transporters, GLUT9 appears to be a urate transporter while GLUT13 is a proton/myoinositol cotransporter. The physiologic substrates of some GLUTs remain to be established. The GLUTs are expressed in a tissue specific manner where affinity, specificity, and capacity for substrate transport are paramount for tissue function. Although great strides have been made in characterizing GLUT-catalyzed monosaccharide transport and mapping GLUT membrane topography and determinants of substrate specificity, a unifying model for GLUT structure and function remains elusive. The GLUTs play a major role in carbohydrate homeostasis and the redistribution of sugar-derived carbons among the various organ systems. This is accomplished through a multiplicity of GLUT-dependent glucose sensing and effector mechanisms that regulate monosaccharide ingestion, absorption,distribution, cellular transport and metabolism, and recovery/retention. Glucose transport and metabolism have coevolved in mammals to support cerebral glucose utilization.
authors.affiliation: Department of Biochemistry & Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Cura
authors.forename: Anthony
authors.initials: A
authors.lastname: Carruthers
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000502:physiology; D050260:Carbohydrate Metabolism / Q000502:physiology*; D057486:Carbon Cycle / Q000502:physiology; D005947:Glucose / Q000378:metabolism; D051246:Glucose Transport Proteins, Facilitative / Q000737:chemistry / Q000502:physiology*; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary
chemical_list: D051246:Glucose Transport Proteins, Facilitative; D008565:Membrane Proteins; D005947:Glucose