pfam14738: PaaSYMP (this model, PSSM-Id:373258 is obsolete and has been replaced by 464290)
Solute carrier (proton/amino acid symporter), TRAMD3 or PAT1
PAT1 (proton amino acid transporter 1), also known as TRAMD3 of AAT-1, is the molecular correlate of the intestinal imino acid carrier. It is a proton-amino acid co-transporter having a stoichiometry of 1:1. Due to its mechanism, PAT1 activity increases at acidic pH, which correlates well with the acidic micro-climate close to the brush-border in the intestine. Glycine, proline, and alanine are the preferred substrates of the transporter. The maximum velocity is similar for the three substrates. All substrates are transported with low affinity, showing Km values in the range of 2-10 mM. The transporter does not discriminate between L- and D-isoforms of these amino acids; in addition, beta-alanine is transported with similar affinity as alpha-alanine. Similar to the IMINO transporter, the amino acid analog MeAIB is recognized by PAT1. The transporter is strongly expressed in the small intestine, colon, kidney, and brain.
Jiyao W et al.(2023). "The conserved domain database in 2023.",