The fatty acid translocase (FAT)/CD36 and the glucose transporter GLUT4 are localized in different cellular compartments in rat cardiac muscle.
The fatty acid translocase (FAT)/CD36 plays an important role in the acute regulation of fatty acid uptake in muscle tissue. We studied the subcellular distribution of FAT/CD36 in rat cardiac muscle after in vivo insulin stimulation by membrane fractionation and immunoisolation of GLUT4- and FAT/CD36-vesicles. FAT/CD36 was equally present in both plasma and microsomal membranes with no effect of insulin on the cellular distribution, whereas GLUT4 increased 2- to 3-fold in the plasma membrane. FAT/CD36 resides in one intracellular pool, whereas GLUT4 is present in two distinct pools. Immunoadsorption of GLUT4-vesicles indicated that FAT/CD36 is undetectable in these vesicles. Likewise, no GLUT4 could be detected in FAT/CD36-vesicles. These vesicles contain a high amount of Rab11 that remained unaffected after insulin stimulation, whereas Rab11 increased about 3-fold in the GLUT4-vesicles in response to insulin. These data show that GLUT4 and FAT/CD36 do not co-localize in cardiac muscle and that FAT/CD36 is not redistributed in response to insulin in the heart. Rab11 may be involved in endosomal recycling of FAT/CD36, however, insulin-associated Rab11 functions appear to be limited to GLUT4-vesicles.
Müller
Heidi
H
Molecular Cardiology, Department of Clinical Biochemistry and Pathobiochemistry, German Diabetes Research Institute, Düsseldorf D-40225, Germany.
Deckers
Karin
K
Eckel
Jürgen
J
D000818:Animals; D018955:CD36 Antigens; D002451:Cell Compartmentation; D002462:Cell Membrane / Q000737:chemistry; D022162:Cytoplasmic Vesicles / Q000737:chemistry; D051275:Glucose Transporter Type 4; D006321:Heart / Q000187:drug effects; D007328:Insulin / Q000494:pharmacology; D008297:Male; D008562:Membrane Glycoproteins / Q000032:analysis*; D008861:Microsomes / Q000737:chemistry; D009004:Monosaccharide Transport Proteins / Q000032:analysis*; D009124:Muscle Proteins; D009206:Myocardium / Q000737:chemistry*; D027361:Organic Anion Transporters / Q000032:analysis*; D051381:Rats; D017208:Rats, Wistar
D018955:CD36 Antigens; D051275:Glucose Transporter Type 4; D007328:Insulin; D008562:Membrane Glycoproteins; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D027361:Organic Anion Transporters; C495694:Slc2a4 protein, rat