The first intracellular loop of GLUT4 contains a retention motif.
Glucose transporter GLUT4 (also known as SLC2A4) plays a major role in glucose homeostasis and is efficiently retained intracellularly in adipocytes and myocytes. To simplify the analysis of its retention, here, various intracellular GLUT4 domains were fused individually to reporter molecules. Of the four short cytoplasmic loops of GLUT4, only the first nine-residue-long loop conferred intracellular retention of truncated forms of the transferrin receptor and CD4 in adipocytes. In contrast, the same loop of GLUT1 was without effect. The reporter molecules to which the first loop of GLUT4 was fused localized, unlike GLUT4, to the trans-Golgi network (TGN), possibly explaining why these molecules did not respond to insulin. The retention induced by the GLUT4 loop was specific to adipocytes as it did not induce retention in preadipocytes. Of the SQWLGRKRA sequence that constitutes this loop, mutation of either the tryptophan or lysine residue abrogated reporter retention. Mutation of these residues individually into alanine residues in the full-length GLUT4 molecule resulted in a decreased retention for GLUT4-W105A. We conclude that the first intracellular loop of GLUT4 contains the retention motif WLGRK, in which W105 plays a prominent role.
Inserm U1062, INRA1260, Aix Marseille University, Faculty of Medicine, Marseille F-13385, France.
Maya
M
Talantikite
Inserm U895, Mediterranean Research Center for Molecular Medicine (C3M), Nice F-06204, France.
Marion
M
Berenguer
Inserm U1062, INRA1260, Aix Marseille University, Faculty of Medicine, Marseille F-13385, France.
Teresa
T
Gonzalez
Inserm U1062, INRA1260, Aix Marseille University, Faculty of Medicine, Marseille F-13385, France.
Marie Christine
MC
Alessi
Inserm U1062, INRA1260, Aix Marseille University, Faculty of Medicine, Marseille F-13385, France.
Marjorie
M
Poggi
Inserm U1062, INRA1260, Aix Marseille University, Faculty of Medicine, Marseille F-13385, France.
Franck
F
Peiretti
Inserm U1062, INRA1260, Aix Marseille University, Faculty of Medicine, Marseille F-13385, France Inserm U895, Mediterranean Research Center for Molecular Medicine (C3M), Nice F-06204, France roland.govers@univ-amu.fr.
Roland
0000-0003-1359-5333
R
Govers
D041721:3T3-L1 Cells; D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism; D020816:Amino Acid Motifs; D000818:Animals; D015704:CD4 Antigens / Q000378:metabolism; D004252:DNA Mutational Analysis; D017930:Genes, Reporter; D051275:Glucose Transporter Type 4 / Q000737:chemistry* / Q000378:metabolism*; D007328:Insulin / Q000494:pharmacology; D042541:Intracellular Space / Q000378:metabolism; D051379:Mice; D009154:Mutation / Q000235:genetics; D000072417:Protein Domains; D017433:Protein Structure, Secondary; D011990:Receptors, Transferrin / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013329:Structure-Activity Relationship; D021601:trans-Golgi Network / Q000187:drug effects / Q000378:metabolism
D015704:CD4 Antigens; D051275:Glucose Transporter Type 4; D007328:Insulin; D011990:Receptors, Transferrin; D011993:Recombinant Fusion Proteins
Adipocytes; Chimera; GLUT4; Insulin; Intracellular retention; Motif; Reporter