ATP-sensitive Binding of a 70-kDa Cytosolic Protein to the Glucose Transporter in Rat Adipocytes
| Autor: | Shuhui Xiong, Yanwei Shi, Sam Jayanth Samuel, Mohsen Lachaal, Hongzhi Liu, Chan Y. Jung |
|---|---|
| Rok vydání: | 1995 |
| Předmět: |
Male
Monosaccharide Transport Proteins Recombinant Fusion Proteins Molecular Sequence Data Plasma protein binding Biochemistry Rats Sprague-Dawley chemistry.chemical_compound Adenosine Triphosphate Cytosol Adipocytes Animals Insulin Molecular Biology DNA Primers Glutathione Transferase Base Sequence biology Glucose transporter Proteins Cell Biology Fusion protein Rats chemistry Phosphoprotein Phosphoserine biology.protein GLUT2 GLUT1 GLUT4 Protein Binding |
| Zdroj: | Journal of Biological Chemistry. 270:7869-7875 |
| ISSN: | 0021-9258 |
| DOI: | 10.1074/jbc.270.14.7869 |
| Popis: | We have identified a 70-kDa cytosolic protein (GTBP70) in rat adipocytes that binds to glutathione S-transferase fusion proteins corresponding to the cytoplasmic domains of the facilitative glucose transporter isoforms Glut1, Glut2, and Glut4. GTBP70 did not bind to irrelevant fusion proteins, indicating that the binding is specific to the glucose transporter. GTBP70 binding to the glucose transporter showed little isoform specificity but was significantly subdomain-specific; it bound to the C-terminal domain and the central loop, but not to the N-terminal domain of Glut4. The GTBP70 binding to Glut4 was not affected by the presence of 2 mM EDTA, 2.4 mM Ca2+, or 150 mM K+. The binding was inhibited by ATP in a dose-dependent manner, with 50% inhibition at 10 mM ATP. This inhibition was specific to ATP, as ADP and AMP-PCP (adenosine 5'-(beta, gamma-methylenetriphosphate)) were without effect. GTBP70 did not react with antibodies against phosphotyrosine, phosphothreonine, or phosphoserine, suggesting that it is not a phosphoprotein. The binding of GTBP70 to Glut4 was not affected by the pretreatment of adipocytes with insulin. When these experiments were repeated using rat hepatocyte cytosols, no ATP-sensitive 70-kDa protein binding to the glucose transporter fusion proteins was evident, suggesting that either GTBP70 expression or its function is cell-specific. These findings strongly suggest the possibility that GTBP70 may play a key role in glucose transporter regulation in insulin target cells such as adipocytes. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|