Identification and characterization of p49/STRAP as a novel GLUT4-binding protein.
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.
Lisinski
Ivonne
I
EDMNS/DB/NIDDK/NIH, Bethesda, MD, USA.
Matsumoto
Hideko
H
Yver
Dena R
DR
Schürmann
Annette
A
Cushman
Samuel W
SW
Al-Hasani
Hadi
H
D000273:Adipose Tissue / Q000166:cytology / Q000378:metabolism*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000737:chemistry; D051275:Glucose Transporter Type 4 / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D025941:Protein Interaction Mapping; D051381:Rats; D014157:Transcription Factors / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D020798:Two-Hybrid System Techniques
D051275:Glucose Transporter Type 4; D007328:Insulin; C495694:Slc2a4 protein, rat; D014157:Transcription Factors; C496544:p49-STRAP protein, mouse