title: The glut 1 glucose transporter interacts with calnexin and calreticulin.
abstract: Calnexin is an integral membrane protein that acts as a chaperone during glycoprotein folding in the endoplasmic reticulum. Cross-linking studies were carried out with the aim of investigating the interactions of calnexin with glycoproteins in vitro. A truncated version of the integral membrane glycoprotein Glut 1 (GT155) was synthesized in a rabbit reticulocyte translation system in the presence of canine pancreatic microsomes. Following immunoprecipitation with an anticalnexin antiserum, a cross-linker-independent association was observed between GT155 and calnexin. In addition, the anti-calnexin antiserum immunoprecipitated a UV-dependent cross-linking product consisting of GT155 and a protein of approximately 60 kDa designated CAP-60 (calnexin-associated protein of 60 kDa). Both the GT155-calnexin and the GT155-CAP-60 interactions were dependent on the presence of a correctly modified oligosaccharide group on GT155, a characteristic of many calnexin interactions. A GT155 mutant that was not glycosylated (AGGT155) did not associate with calnexin or CAP-60. Calreticulin, the soluble homologue of calnexin, was also shown to interact with GT155 only when the protein bore a correctly modified oligosaccharide group. Thus, our data show that both calnexin and calreticulin with Glut 1 in a glycosylation-dependent manner.
authors.affiliation: School of Biological Sciences, University of Manchester, 2.205 Stopford Building, Oxford Road, Manchester M13 9PT, United Kingdom.
authors.forename: J D
authors.initials: JD
authors.lastname: Oliver
authors.forename: R C
authors.initials: RC
authors.lastname: Hresko
authors.forename: M
authors.initials: M
authors.lastname: Mueckler
authors.forename: S
authors.initials: S
authors.lastname: High
mesh_terms: D000818:Animals; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D037281:Calnexin; D037282:Calreticulin; D003432:Cross-Linking Reagents; D004285:Dogs; D051272:Glucose Transporter Type 1; D006031:Glycosylation; D006801:Humans; D066298:In Vitro Techniques; D008861:Microsomes / Q000378:metabolism; D018832:Molecular Chaperones / Q000378:metabolism; D009004:Monosaccharide Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D011817:Rabbits; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012156:Reticulocytes / Q000378:metabolism; D012261:Ribonucleoproteins / Q000378:metabolism*; D014466:Ultraviolet Rays
chemical_list: D002135:Calcium-Binding Proteins; D037282:Calreticulin; D003432:Cross-Linking Reagents; D051272:Glucose Transporter Type 1; D018832:Molecular Chaperones; D009004:Monosaccharide Transport Proteins; D010446:Peptide Fragments; D011994:Recombinant Proteins; D012261:Ribonucleoproteins; C495677:SLC2A1 protein, human; D037281:Calnexin