Amino acid-proton symporter. Stereospecific transporter with a broad specificity for GABA, tryptophan and both neutral and basic amino acids. High affinity transport of cationic amino acids. Inhibited by carbonylcyanide m-chlorophenylhydrazone and 2,4-dinitrophenol. Not found in vacuole membrane. Expressed in the root phloem. Detected in stamens, in cotyledons, and in major veins of mature leaves. Induced in the connective tissue of stamens shortly before dehiscence. No visible phenotype. Belongs to the amino acid/polyamine transporter 2 family. Amino acid/auxin permease (AAAP) (TC 2.A.18.2) subfamily.