Identification and characterization of p49/STRAP as a novel GLUT4-binding protein.
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Lisinski I, Matsumoto H, Yver DR, Schurmann A, Cushman SW, Al-Hasani H
Identification and characterization of p49/STRAP as a novel GLUT4-binding protein.
Biochem Biophys Res Commun. 2006 Jun 16;344(4):1179-85. Epub 2006 Apr 21.
- PubMed ID
- 16647043 [ View in PubMed]
- Abstract
To identify novel regulatory components involved in the recycling of the insulin-responsive glucose transporter GLUT4, we have used the yeast two-hybrid system to isolate GLUT4-binding proteins from a rat adipose cell cDNA library. We found a 49-kDa protein (p49/STRAP) that specifically interacts with an acidic amino acid motif (Q7IGSEDG) in the N-terminus of GLUT4. Confocal immunofluorescence microscopy of primary rat adipose cells shows co-localization of myc-p49 with GLUT4 and also with the ER-resident protein calnexin. Insulin stimulation had no effect on GLUT4-binding and subcellular distribution of p49 in adipose cells. However, overexpression of the GLUT4-binding domain of p49 in adipose cells reduces protein synthesis and cell-surface expression of GLUT4, but not of GLUT8. Moreover, cell-surface expression of a p49-binding-deficient GLUT4 mutant (ED/QN) is also reduced. Kinetic analysis of HA-epitope-tagged GLUT4 protein synthesis indicates a possible role of p49 in biosynthesis and/or processing of GLUT4 in adipose cells.