CD98 is a glycoprotein that is a heterodimer composed of SLC3A2 and SLC7A5 that forms the large neutral amino acid transporter (LAT1). LAT1 is a heterodimeric membrane transport protein that preferentially transports branched-chain (valine, leucine, isoleucine) and aromatic (tryptophan, tyrosine) amino acids. LAT is highly expressed in brain capillaries (which form the blood–brain barrier) relative to other tissues.
A functional LAT1 transporter is composed of two proteins encoded by two distinct genes:
- 4F2hc/CD98 heavy subunit protein encoded by the SLC3A2 gene
- CD98 light subunit protein encoded by the SLC7A5 gene