Cutting edge: Primary structure of the light chain of fusion regulatory protein-1/CD98/4F2 predicts a protein with multiple transmembrane domains that is almost identical to the amino acid transporter E16

The CD98 light chain (CD98LC) was copurified from HeLa S3 cells by an affin ity chromatography using a mAb specific for the fusion regulatory protein-1 (FRP-1) which is identical to the CD98 heavy chain. On the basis of the N- terminal sequence (63 amino acids) of purified CD98LC polypeptide, we have cloned a PCR fragment (155 bp) from a HeLa S3 cDNA library and finally obta ined a full cDNA clone encoding the CD98LC, Fluorescence in situ hybridizat ion analysis using the cDNA assigned the CD98LC gene to the long arm of hum an chromosome 16 (16q24), The predicted amino acid sequence suggested that CD98LC is a protein with multiple transmembrane domains and is almost ident ical to the amino acid transporter E16. Resting monocytes and lymphocytes e xpressed CD98LC as analyzed by a newly isolated anti-CD98LC mAb, which show ed cross-reactivity with insect Sf9 cells as well as with various mammalian cell lines.