Show simple item record

dc.contributor.authorSultzman, Lisa A.
dc.contributor.authorCarruthers, Anthony
dc.date2022-08-11T08:08:51.000
dc.date.accessioned2022-08-23T16:10:03Z
dc.date.available2022-08-23T16:10:03Z
dc.date.issued1999-06-03
dc.date.submitted2008-03-21
dc.identifier.citationBiochemistry. 1999 May 18;38(20):6640-50. <a href="http://dx.doi.org/10.1021/bi990130o">Link to article on publisher's site</a>
dc.identifier.issn0006-2960 (Print)
dc.identifier.doi10.1021/bi990130o
dc.identifier.pmid10350483
dc.identifier.urihttp://hdl.handle.net/20.500.14038/32844
dc.description.abstractThe human erythrocyte sugar transporter is thought to function either as a simple carrier (sugar import and sugar export sites are presented sequentially) or as a fixed-site carrier (sugar import and sugar export sites are presented simultaneously). The present study examines each hypothesis by analysis of the rapid kinetics of reversible cytochalasin B binding to the sugar export site in the presence and absence of sugars that bind to the sugar import site. Cytochalasin B binding to the purified, human erythrocyte glucose transport protein (GLUT1) induces quenching of GLUT1 intrinsic tryptophan fluorescence. The time-course of GLUT1 fluorescence quenching reflects a second-order process characterized by simple exponential kinetics. The pseudo-first-order rate constant describing fluorescence decay (kobs) increases linearly with [cytochalasin B] while the extent of fluorescence quenching increases in a saturable manner with [cytochalasin B]. Rate constants for cytochalasin B binding to GLUT1 (k1) and dissociation from the GLUT1.cytochalasin B complex (k-1) are obtained from the relationship: kobs = k-1 + k1[cytochalasin B]. Low concentrations of maltose, D-glucose, 3-O-methylglucose, and other GLUT1 import-site reactive sugars increase k-1(app) and reduce k1(app) for cytochalasin B interaction with GLUT1. Higher sugar concentrations decrease k1(app) further. The simple carrier mechanism predicts that k1(app) alone is modulated by import- and export-site reactive sugars and is thus incompatible with these findings. These results are consistent with a fixed-site carrier mechanism in which GLUT1 simultaneously presents cooperative sugar import and export sites.
dc.language.isoen_US
dc.relation<a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10350483&dopt=Abstract ">Link to article in PubMed</a>
dc.relation.urlhttp://dx.doi.org/10.1021/bi990130o
dc.subject3-O-Methylglucose; Binding Sites; Biological Transport; Blood Glucose; Cytochalasin B; Erythrocytes; Glucose Transporter Type 1; Humans; Kinetics; Ligands; Liposomes; Maltose; Monosaccharide Transport Proteins; Proteolipids; Spectrometry, Fluorescence
dc.subjectLife Sciences
dc.subjectMedicine and Health Sciences
dc.titleStop-flow analysis of cooperative interactions between GLUT1 sugar import and export sites
dc.typeJournal Article
dc.source.journaltitleBiochemistry
dc.source.volume38
dc.source.issue20
dc.identifier.legacycoverpagehttps://escholarship.umassmed.edu/gsbs_sp/14
dc.identifier.contextkey467864
html.description.abstract<p>The human erythrocyte sugar transporter is thought to function either as a simple carrier (sugar import and sugar export sites are presented sequentially) or as a fixed-site carrier (sugar import and sugar export sites are presented simultaneously). The present study examines each hypothesis by analysis of the rapid kinetics of reversible cytochalasin B binding to the sugar export site in the presence and absence of sugars that bind to the sugar import site. Cytochalasin B binding to the purified, human erythrocyte glucose transport protein (GLUT1) induces quenching of GLUT1 intrinsic tryptophan fluorescence. The time-course of GLUT1 fluorescence quenching reflects a second-order process characterized by simple exponential kinetics. The pseudo-first-order rate constant describing fluorescence decay (kobs) increases linearly with [cytochalasin B] while the extent of fluorescence quenching increases in a saturable manner with [cytochalasin B]. Rate constants for cytochalasin B binding to GLUT1 (k1) and dissociation from the GLUT1.cytochalasin B complex (k-1) are obtained from the relationship: kobs = k-1 + k1[cytochalasin B]. Low concentrations of maltose, D-glucose, 3-O-methylglucose, and other GLUT1 import-site reactive sugars increase k-1(app) and reduce k1(app) for cytochalasin B interaction with GLUT1. Higher sugar concentrations decrease k1(app) further. The simple carrier mechanism predicts that k1(app) alone is modulated by import- and export-site reactive sugars and is thus incompatible with these findings. These results are consistent with a fixed-site carrier mechanism in which GLUT1 simultaneously presents cooperative sugar import and export sites.</p>
dc.identifier.submissionpathgsbs_sp/14
dc.contributor.departmentDepartment of Biochemistry and Molecular Pharmacology
dc.contributor.departmentGraduate School of Biomedical Sciences
dc.source.pages6640-50


This item appears in the following Collection(s)

Show simple item record