Amino acid-proton symporter. Transporter with a broad specificity for neutral and acidic amino acids. Basic amino acids are only marginally transported. Involved in import of amino acids into the tapetum cells for synthesis of compounds important for microspore structure. Inhibited by diethylstibestrol (DES), 2,4-dinitrophenol (DNP) and carbonlycyanide m-chlorophenylhydrazone (CCCP). Optimum pH is 4-5. Expressed in flower buds and to lower levels in leaves and stems. Not detected in roots and siliques. Restricted to the tapetum cell layer. Belongs to the amino acid/polyamine transporter 2 family. Amino acid/auxin permease (AAAP) (TC 2.A.18.2) subfamily.