| Nucleoside transporters (NTs) are transmembrane proteins responsible for the movement of nucleosides across cell membranes. Since NTs also transport clinically important nucleoside analog drugs, detailed regulatory and structural analyses will provide increased understanding on mechanisms of regulation, substrate binding and translocation. This knowledge can then aid in the improvement of chemotherapies by facilitating the design of better targeted drugs and increasing the susceptibility of afflicted cells to these drugs. Little is known on the regulation of NTs. However, current data suggest that hENT1, the predominant NT in humans, could be regulated by direct phosphorylation by PKC which affects the affinity of hENT1 proteins at the plasma membrane. To further support this model, I propose that hENT1 is phosphorylated and that these sites are located within the large intracellular loop of the protein. Tandem affinity purification of hENT1 and phospho-peptide mapping using MALDI-TOF mass spectrometry was conducted to accomplish this task. (Abstract shortened by UMI.)... |
