Protein kinase C regulates amino acid transporter ATB0,+

ATB(0,+) (SLC6/114) is a transporter specific towards neutral and cationic amino acids, known to be up-regulated in malignant tumor cells. We cloned cDNA for rATB(0,+) and expressed it in HEK 293 cells. The ATB(0,+) 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 ATB(0,+) interaction with PKC alpha, but not with other classical or novel PKC isoforms. Immunocytochemistry experiments showed a transfer of PKC alpha to plasma membrane upon phorbol ester activation and co-localization with ATB(0,+). The observed regulation of ATB(0,+) by PKC correlates with high activity of both proteins reported for cancer cells. (C) 2012 Elsevier Inc. All rights reserved.