We showed previously that GLUT-1 glucose transporter is associated with sto
matin (band 7.2b) in human red blood cell membranes and in Clone 9 cells. W
e show here that in a mixed population of stably transfected cells, overexp
ression of either murine or human stomatin resulted in 35-50% reduction in
the basal rate of glucose transport. Moreover, there was a correlation betw
een increased expression of stomatin and depression in the rate of glucose
transport. In two clones chosen for further study, the similar to 10% and s
imilar to 70% reduction in basal rate of glucose transport was associated w
ith 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 assoc
iated with a large amount of stomatin as a coimmunoprecipitant. Employing e
xtracts of cells overexpressing human stomatin, we found that stomatin boun
d 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 fus
ion protein containing the 66-amino acid central loop of GLUT-1. Rat stomat
in 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-pro
tein interaction.