L-type amino acid transporter 1 (LAT1) is responsible for mediating the transport of amino acids into highly proliferative cells. LAT1 is Na⁺-independent amino acid transporter that transports branched-chain and aromatic neutral amino acids including isoleucine, histidine, leucine, methionine, phenylalanine, tryptophan, tyrosine, methionine and valine. LAT1 forms heterodimeric complexes with the 4F2 cell-surface antigen heavy chain (4F2hc) via a disulfide bond ^1,2. Structurally, LAT1 has 12 membrane spanning domains with intracellular N- and C-terminal tails³.

LAT1 mRNA expression can be found in various tissues such as the brain, spleen, placenta, and testis. High protein levels are particularly detected in pancreatic islet. In cells, LAT1 is localized to the basolateral membrane of polarized epithelia^1,2.

Studies show that upregulation in LAT1 protein is linked and associated with cancer cell proliferation and is highly expressed in tumor cell lines including oral squamous cell carcinoma, esophageal carcinoma, gastric cancer, prostate cancer, non-small cell lung carcinoma, biliary tract cancer, pancreatic cancer, and breast cancer².