Amino acid (AA) transporters may act as sensors, as well as carriers, of tissue nutrient
supplies. This review considers recent advances in our understanding of the AA-sensing
functions of AA transporters in both epithelial and nonepithelial cells. These transporters
mediate AA exchanges between extracellular and intracellular fluid compartments,
delivering substrates to intracellular AA sensors. AA transporters on endosomal (eg,
lysosomal) membranes may themselves function as intracellular AA sensors. AA …