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. glycine(in) + H(+)(in) = glycine(out) + H(+)(out) H(+)(in) + L-alanine(in) = H(+)(out) + L-alanine(out) D-alanine(in) + H(+)(in) = D-alanine(out) + H(+)(out) H(+)(out) + L-proline(out) = H(+)(in) + L-proline(in) D-proline(out) + H(+)(out) = D-proline(in) + H(+)(in) 4-hydroxy-L-proline(in) + H(+)(in) = 4-hydroxy-L-proline(out) + H(+)(out) H(+)(in) + L-serine(in) = H(+)(out) + L-serine(out) D-serine(out) + H(+)(out) = D-serine(in) + H(+)(in) beta-alanine(in) + H(+)(in) = beta-alanine(out) + H(+)(out) 4-aminobutanoate(in) + H(+)(in) = 4-aminobutanoate(out) + H(+)(out) H(+)(in) + sarcosine(in) = H(+)(out) + sarcosine(out) H(+)(in) + N,N-dimethylglycine(in) = H(+)(out) + N,N-dimethylglycine(out) Abundantly expressed in kidney and muscle. Expressed in the S1 segment of the proximal tubule close to the glomerulus. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting distinct genetic loci, including the gene represented in this entry. Mutations in SLC36A2 that retain residual transport activity result in the IG phenotype only when combined with haploinsufficiency of the imino acid transporter SLC6A20 or deficiency of the neutral amino acid transporter SLC6A19. Additional polymorphisms and mutations in SLC6A18 can contribute to iminoglycinuria in some families. Belongs to the amino acid/polyamine transporter 2 family.