FIG. 1.

Interaction between glucose and lipids at the level of insulin signaling and mitochondrial function in skeletal muscle. Glucose is taken up via glucose transporter 4 (glut4) into the myocyte, activated to glucose-6-phosphate (G6P), and then oxidized in the mitochondria or stored as glycogen. Free fatty acids are taken up via fatty acid transporter protein 1 (fatp1) into the myocyte, activated to fatty acyl coenzyme A (FACoA), and then transported by the carnitine palmitoyltransferase 1 (cpt1) into mitochondria for oxidation (OX), or stored as triyglycerides, or inhibit insulin signaling by serine phosphorylation of IRS-1. Both glucose and lipid OX fuel the tricarboxylic acid cycle and serve to produce ATP via ATP synthase (ATPase). To see this illustration in color, the reader is referred to the web version of this article at www.liebertpub.com/ars