Sequence determinants of GLUT1 oligomerization: analysis by homology-scanning mutagenesis.

摘要: The human blood-brain barrier glucose transport protein (GLUT1) forms homodimers and homotetramers in detergent micelles cell membranes, where the GLUT1 oligomeric state determines behavior. neuronal transporter GLUT3 do not form heterocomplexes embryonic kidney 293 (HEK293) cells as judged by co-immunoprecipitation assays. Using homology-scanning mutagenesis which domains are substituted with equivalent vice versa, we show that transmembrane helix 9 (TM9) is necessary for optimal association of GLUT1-GLUT3 chimeras parental HEK cells. TMs 2, 5, 8, 11 also contribute to a less abundant heterocomplex. Cell surface containing TM9 4-fold more catalytically active than TM9. display allosteric Size exclusion chromatography solubilized, purified resolves GLUT1/lipid/detergent 6- 10-nm Stokes radius particles, correspond dimers tetramers, respectively. Studies GLUTs expressed solubilized from whereas 6-nm particle. Substitution causes chimeric resolve particles. mixture 4-nm We discuss these findings context determinants GLUT structure function. Background: homo-oligomers but does hetero-oligomerize GLUT3. Results: substitution promotes association. Conclusion: states activities determined sequence. Significance: activity some multisubunit complexes their quaternary structure.