Protein kinase C regulates amino acid transporter ATB0,+

ATB0,+ (SLC6A14) is a transporter specific towards neutral and cationic amino acids, known to be up-regulated in malignant tumor cells. We cloned cDNA for rATB0,+ and expressed it in HEK 293 cells. The ATB0,+ over-expression correlated with increased l-leucine transport, stimulated by protein kinase C (PKC) activator and attenuated by PKC inhibitors. Transport stimulation was correlated with phosphorylation on serine moiety of the transporter and its augmented plasma membrane presence. Immunoprecipitation experiments demonstrated ATB0,+ interaction with PKCα, but not with other classical or novel PKC isoforms. Immunocytochemistry experiments showed a transfer of PKCα to plasma membrane upon phorbol ester activation and co-localization with ATB0,+. The observed regulation of ATB0,+ by PKC correlates with high activity of both proteins reported for cancer cells.

► Amino acid transporter ATB0,+ is phosphorylated by protein kinase C (PKC). ► PKCα interacts with ATB0,+ and co-localizes with the transporter at plasma membrane. ► Activation of PKC correlates with ATB0,+ activity and plasma membrane presence.