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 (SLC7A5) 4F2hc (SLC3A2) kidney, liver, intestine, brain, heart lung, blood–brain barrier large neutral amino acids, thyroid hormones micromolar no – L LAT2 (SLC7A8) 4F2hc (SLC3A2) kidney, intestine, brain, liver, muscle, heart, lung smaller neutral amino acids millimolar no – y+L y+LAT1 (SLC7A7) 4F2hc (SLC3A2) kidney, intestine, lung, erythrocytes, leukocytes large neutral amino acids, dibasic amino acid exchange micromolar yes Lysinuric protein intolerance y+L y+LAT2 (SLC7A6) 4F2hc (SLC3A2) brain, intestine, heart, kidney, lung, liver neutral amino acids, dibasic amino acid exchange, glutamine/arginine exchange millimolar yes – xc− xCT (SLC7A11) 4F2hc (SLC3A2) macrophages, liver, kidney, brain glutamine/cystine exchange no – asc ascAT1 (SLC7A10) 4F2hc (SLC3A2) brain, lung, small intestine, kidney small neutral amino acids no – b0,+ b0,+AT1 (SLC7A9) rBAT (SLC3A1) kidney, intestine, brain neutral/dibasic amino acids no Cystinuria type I
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