Biochemical and functional heterogeneity of rat adipocyte glucose transporters

R. Horuk, S. Matthaei, J. M. Olefsky, D. L. Baly, S. W. Cushman, Ian Simpson

Research output: Contribution to journalArticle

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Abstract

We have studied the biochemical mechanism of insulin action on glucose transport in the rat adipocyte. Plasma membranes and low-density microsomes were prepared by differential ultracentrifugation of basal and insulin-stimulated cells. The photochemical cross-linking agent hydroxysuccinimidyl-4-azidobenzoate was used to covalently bind [3H]cytochalasin B to the glucose transporter which migrated as a 45-50-kDa protein on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Isoelectric focusing of the eluted 40-55-kDa proteins revealed two peaks of D-glucose-inhibitable [3H]cytochalasin B radioactivity focusing at pH 6.4 and 5.6 when low-density microsomes were used as the starting material. In contrast, only one D-glucose inhibitable peak, focusing at pH 5.6, was found in plasma membranes. Pretreatment of the cells with insulin led to a marked redistribution of the pH 5.6 form of the glucose transporter from low-density microsomes to plasma membranes with no effect on the pH 6.4 form of the glucose transporter. Following isolation from the isoelectric focusing and sodium dodecyl sulfate-polyacrylamide gels, both glucose transporter isoforms were shown to cross-react with an antiserum raised against the purified human erythrocyte glucose transporter. Following incubation of [3H]cytochalasin B-labeled low-density microsomal and plasma membranes with neuraminidase, the pH 5.6 transporter isoform was shifted on isoelectric focusing to a more basic pH, while the pH 6.4 isoform was not affected. These data demonstrate that: 1) there is a heterogeneity of glucose transporter species in the intracellular pool while the plasma membrane transporters are more uniform in structure. 2) The pH 5.6 glucose transporter isoform is translocated by insulin from the low-density microsomes to the plasma membrane but the pH 6.4 isoform is not sensitive to insulin. 3) Differential sensitivity of the glucose transporter isoforms to neuraminidase suggests that the heterogeneity is at least partially due to differences in glycosylation state.

Original languageEnglish (US)
Pages (from-to)1823-1828
Number of pages6
JournalJournal of Biological Chemistry
Volume261
Issue number4
StatePublished - 1986

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Facilitative Glucose Transport Proteins
Adipocytes
Cell membranes
Rats
Protein Isoforms
Cytochalasin B
Insulin
Cell Membrane
Microsomes
Isoelectric Focusing
Neuraminidase
Glucose
Sodium Dodecyl Sulfate
Glucose Transporter Type 1
Glycosylation
Membrane Transport Proteins
Radioactivity
Electrophoresis
Ultracentrifugation
Immune Sera

All Science Journal Classification (ASJC) codes

  • Biochemistry

Cite this

Horuk, R., Matthaei, S., Olefsky, J. M., Baly, D. L., Cushman, S. W., & Simpson, I. (1986). Biochemical and functional heterogeneity of rat adipocyte glucose transporters. Journal of Biological Chemistry, 261(4), 1823-1828.
Horuk, R. ; Matthaei, S. ; Olefsky, J. M. ; Baly, D. L. ; Cushman, S. W. ; Simpson, Ian. / Biochemical and functional heterogeneity of rat adipocyte glucose transporters. In: Journal of Biological Chemistry. 1986 ; Vol. 261, No. 4. pp. 1823-1828.
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Horuk, R, Matthaei, S, Olefsky, JM, Baly, DL, Cushman, SW & Simpson, I 1986, 'Biochemical and functional heterogeneity of rat adipocyte glucose transporters', Journal of Biological Chemistry, vol. 261, no. 4, pp. 1823-1828.

Biochemical and functional heterogeneity of rat adipocyte glucose transporters. / Horuk, R.; Matthaei, S.; Olefsky, J. M.; Baly, D. L.; Cushman, S. W.; Simpson, Ian.

In: Journal of Biological Chemistry, Vol. 261, No. 4, 1986, p. 1823-1828.

Research output: Contribution to journalArticle

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AU - Horuk, R.

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Horuk R, Matthaei S, Olefsky JM, Baly DL, Cushman SW, Simpson I. Biochemical and functional heterogeneity of rat adipocyte glucose transporters. Journal of Biological Chemistry. 1986;261(4):1823-1828.