Heterodimeric amino-acid transporter
Heterodimeric amino-acid transporters are a family of transport proteins that facilitate the transport of certain amino acids across cell membranes. Each comprises a light and a heavy protein subunit. Transport activity happens in the light.
The following table lists the members of this family:
| Transport system | Light subunit | Heavy subunit | Tissue distribution | Substrates | Affinity | Sodium dependence | Disease linkage |
| L | LAT1 | 4F2hc | kidney, liver, intestine, brain, heart lung, blood–brain barrier | large neutral amino acids, thyroid hormones | micromolar | no | – |
| L | LAT2 | 4F2hc | kidney, intestine, brain, liver, muscle, heart, lung | smaller neutral amino acids | millimolar | no | – |
| y+L | y+LAT1 | 4F2hc | kidney, intestine, lung, erythrocytes, leukocytes | large neutral amino acids, dibasic amino acid exchange | micromolar | yes | Lysinuric protein intolerance |
| y+L | y+LAT2 | 4F2hc | brain, intestine, heart, kidney, lung, liver | neutral amino acids, dibasic amino acid exchange, glutamine/arginine exchange | millimolar | yes | – |
| xc− | xCT | 4F2hc | macrophages, liver, kidney, brain | glutamine/cystine exchange | no | – | |
| asc | ascAT1 | 4F2hc | brain, lung, small intestine, kidney | small neutral amino acids | no | – | |
| b0,+ | b0,+AT1 | rBAT | kidney, intestine, brain | neutral/dibasic amino acids | no | Cystinuria type I |