Proton-coupled amino acid transporter 2

Electrogenic proton/amino acid symporter with a high selectivity for the small side chains amino acids glycine, alanine and proline, where both L- and D-enantiomers are transported. Extension of the backbone length, as in beta-alanine and 4-aminobutanoate or methylation of the amino group, as in sarcosine and N,N-dimethylglycine, are also tolerated but decrease transport efficiency. A free carboxyl group is preferred.