Phosphatidylinositol 4-kinase, but not phosphatidylinositol 3-kinase, is present in GLUT4-containing vesicles isolated from rat skeletal muscle
| Autor: | S Kristiansen, T Ramlal, Amira Klip |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
Male
Adenosine Time Factors Insulin Receptor Substrate Proteins Monosaccharide Transport Proteins Muscle Proteins Biology Biochemistry chemistry.chemical_compound Phosphatidylinositol 3-Kinases medicine Animals Insulin Phosphatidylinositol Kinase activity Rats Wistar Muscle Skeletal Molecular Biology 1-Phosphatidylinositol 4-Kinase Glucose Transporter Type 4 Vesicle Cell Membrane Glucose transporter Skeletal muscle Cell Biology Phosphoproteins Precipitin Tests Rats Androstadienes Insulin receptor medicine.anatomical_structure chemistry biology.protein Wortmannin GLUT4 Research Article |
| Zdroj: | The Biochemical journal. 335 |
| ISSN: | 0264-6021 |
| Popis: | Insulin stimulates the rate of glucose transport into muscle and adipose cells by translocation of glucose transporter (GLUT4)-containing vesicles from an intracellular storage pool to the surface membrane. This event is mediated through the insulin receptor substrates (IRSs), which in turn activate phosphatidylinositol (PI) 3-kinase isoforms. It has been suggested that insulin causes attachment of PI 3-kinases to the intracellular GLUT4-containing vesicles in rat adipose cells. Furthermore, it has also been shown that GLUT4-containing vesicles in adipose cells contain a PI 4-kinase. In the present study we investigate whether GLUT4-containing vesicles isolated from rat skeletal muscle display PI 3-kinase and/or PI 4-kinase activities. Insulin stimulation caused a rapid increase (5–15-fold increase compared with control) in the intracellular cytosolic IRS-1-associated PI-3 kinase activity. This PI 3-kinase activity was also present in a membrane preparation containing the insulin-regulatable pool of GLUT4 transporters. However, when GLUT4-containing vesicles were isolated by immunoprecipitation from basal and insulin-stimulated (3 min) skeletal muscle, the vesicles displayed PI 4-kinase, but not PI 3-kinase, activity. Insulin did not regulate the PI 4-kinase activity in the GLUT4-containing vesicles. In conclusion, GLUT4-containing vesicles from rat skeletal muscle contain a PI 4-kinase, but not a PI 3-kinase. It is suggested that, in skeletal muscle, insulin causes activation of the IRS/PI 3-kinase complex in an intracellular membrane compartment associated closely with the GLUT4-containing vesicles, but not in the GLUT4-containing vesicles themselves. |
| Databáze: | OpenAIRE |
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