Characteristics of L-NNA transport via ATB0,+. The cloned mouse ATB0,+ was expressed in HRPE cells, and the transport of [3H]-L-NNA (10 μM) was studied. Results represent only ATB0,+-specific transport. (a) Transport of L-NNA in vector-transfected cells and in ATB0,+ cDNA-transfected cells. (b) Inhibition of ATB0,+-specific L-NNA transport by amino acids (5 mM). (c) Saturation kinetics of L-NNA transport via ATB0,+.