Overexpression of stomatin depresses GLUT-1 glucose transporter activity.
We showed previously that GLUT-1 glucose transporter is associated with stomatin (band 7.2b) in human red blood cell membranes and in Clone 9 cells. We show here that in a mixed population of stably transfected cells, overexpression of either murine or human stomatin resulted in 35-50% reduction in the basal rate of glucose transport. Moreover, there was a correlation between increased expression of stomatin and depression in the rate of glucose transport. In two clones chosen for further study, the ~10% and ~70% reduction in basal rate of glucose transport was associated with increases in stomatin mRNA and protein expression without a detectable change in GLUT-1 content in plasma membranes of either clone. In the clone overexpressing high levels of stomatin, immunoprecipitated GLUT-1 was associated with a large amount of stomatin as a coimmunoprecipitant. Employing extracts of cells overexpressing human stomatin, we found that stomatin bound to the glutathione-S-transferase (GST) fusion protein containing the COOH-terminal 42-amino acid segment of GLUT-1 but not to GST alone or a GST fusion protein containing the 66-amino acid central loop of GLUT-1. Rat stomatin cDNA was cloned by RT-PCR and found to be highly homologous to mouse (97%) and human (86%) stomatins. These results suggest that overexpression of stomatin results in a depression in the basal rate of glucose transport by decreasing the "intrinsic" activity of GLUT-1, probably through protein-protein interaction.
Zhang
J Z
JZ
Department of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4951, USA.
Abbud
W
W
Prohaska
R
R
Ismail-Beigi
F
F
D000595:Amino Acid Sequence; D000818:Animals; D001798:Blood Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D002462:Cell Membrane / Q000502:physiology; D002999:Clone Cells; D017124:Conserved Sequence; D005786:Gene Expression Regulation; D005947:Glucose / Q000378:metabolism*; D051272:Glucose Transporter Type 1; D006801:Humans; D007700:Kinetics; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology; D051379:Mice; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014162:Transfection
D001798:Blood Proteins; C488964:Stom protein, mouse; D051272:Glucose Transporter Type 1; D008565:Membrane Proteins; D009004:Monosaccharide Transport Proteins; D012333:RNA, Messenger; C495677:SLC2A1 protein, human; C036860:STOM protein, human; C495678:Slc2a1 protein, mouse; C495679:Slc2a1 protein, rat; D005947:Glucose