Amino-acid permease with rather broad substrate specificity. Transports many amino acids including proline, methionine, leucine, valine, isoleucine, phenylalanine, tryptophan, threonine and tyrosine, but not basic ones (arginine) and citrulline. Functions as a sensor via detection of some amino acids including methionine, leading to a rapid activation of trehalase, a downstream target of PKA