Role of plasma membrane transporters in muscle metabolism

Muscle plays a major role in metabolism. Thus it is a major glucose-utilizi ng tissue in the absorptive state, and changes in muscle insulin-stimulated glucose uptake alter whole-body glucose disposal. In some conditions, musc le preferentially uses lipid substrates, such as fatty acids or ketone bodi es. Furthermore, muscle is the main reservoir of amino acids and protein. T he activity of many different plasma membrane transporters, such as glucose carriers and transporters of carnitine, creatine and amino acids, play a c rucial role in muscle metabolism by catalysing the influx or the efflux of substrates across the cell surface. In some cases, the membrane transport p rocess is subjected to intense regulatory control and may become a potentia l pharmacological target, as is the case with the glucose transporter GLUT4 . The goal of this review is the molecular characterization of muscle membr ane transporter proteins, as well as the analysis of their possible regulat ory role.