Editing Uniporter (section)

=== Large neutral amino acid transporter (LAT1) ===
[[File:Protein SLC3A2 PDB 2dh2.png|thumb|SLC3 protein coding gene for LAT1]]
The '''L-type amino acid transporter (LAT1)''' is a uniporter that mediates the transport of [[Neutral amino acid transporter A|neutral amino acids]] like [[Tryptophan|L-tryptophan]], [[leucine]], [[histidine]], [[proline]], [[alanine]], etc.<ref name="Häfliger P">{{cite journal |vauthors=Häfliger P, Charles RP |title=The L-Type Amino Acid Transporter LAT1-An Emerging Target in Cancer |journal=Int J Mol Sci |volume=20 |issue=10 |date=May 2019 |page=2428 |pmid=31100853 |pmc=6566973 |doi=10.3390/ijms20102428 |doi-access=free }}</ref> [[CD98|LAT1]] favors the transport of amino acids with large branched or [[Amino acid|aromatic side chains]]. The amino acid transporter functions to move essential amino acids into the [[intestinal epithelium]], [[placenta]], and [[Blood–brain barrier|blood-brain barrier]] for cellular processes such as metabolism and cell signaling.<ref name="Bhutia YD">{{cite journal |vauthors=Bhutia YD, Mathew M, Sivaprakasam S, Ramachandran S, Ganapathy V |title=Unconventional Functions of Amino Acid Transporters: Role in Macropinocytosis (SLC38A5/SLC38A3) and Diet-Induced Obesity/Metabolic Syndrome (SLC6A19/SLC6A14/SLC6A6) |journal=Biomolecules |volume=12 |issue=2 |date=January 2022 |page=235 |pmid=35204736 |pmc=8961558 |doi=10.3390/biom12020235 |doi-access=free }}</ref> The transporter is of particular significance in the [[central nervous system]] as it provides the necessary amino acids for protein synthesis and [[Neurotransmitter|neurotransmitter production]] in brain cells.<ref name="Bhutia YD" /> [[Aromatic amino acid]]s like [[phenylalanine]] and [[tryptophan]] are precursors for neurotransmitters like [[dopamine]], [[serotonin]], and [[norepinephrine]].<ref name="Bhutia YD" />

LAT1 is a membrane protein of the [[SLC7A14|SLC7]] family of transporters and works in conjunction with the [[Solute carrier family|SLC3 family]] member [[4F2 cell-surface antigen heavy chain|4F2hc]] to form a [[Protein dimer|heterodimeric]] complex known as the 4F2hc complex.<ref name="Häfliger P" /> The heterodimer consists of a light chain and a heavy chain [[Covalent bond|covalently bonded]] by a [[disulfide bond]]. The light chain is the one that carries out transport, while the heavy chain is needed to stabilize the dimer.<ref name="Häfliger P" />

There is some controversy over whether LAT1 is an uniporter or an [[antiporter]]. The transporter has uniporter characteristics of transporting amino acids into cells in a unidirectional manner down the concentration gradient. However, recently it has been found that the transporter has antiporter characteristics of exchanging neutral amino acids for abundant intracellular amino acids.<ref>{{cite journal |vauthors=Singh N, Ecker GF |title=Insights into the Structure, Function, and Ligand Discovery of the Large Neutral Amino Acid Transporter 1, LAT1 |journal=Int J Mol Sci |volume=19 |issue=5 |date=April 2018 |page=1278 |pmid=29695141 |pmc=5983779 |doi=10.3390/ijms19051278 |doi-access=free }}</ref>  Over-expression of LAT1 has been found in human [[cancer]] and is associated with playing a role in cancer metabolism.<ref>{{cite journal |vauthors=Kanai Y |title=Amino acid transporter LAT1 (SLC7A5) as a molecular target for cancer diagnosis and therapeutics |journal=Pharmacol Ther |volume=230 |issue= |pages=107964 |date=February 2022 |pmid=34390745 |doi=10.1016/j.pharmthera.2021.107964 }}</ref>