CD98 exists as a heterodimer containing a disulphide-linked glycosylated heavy chain and a non-glycosylated light chain. It is a member of the solute carrier family and encodes a cell surface, transmembrane protein. The protein exists as the heavy chain of a heterodimer, covalently bound through disulphide bonds to one of several possible light chains. The encoded transporter plays a role in regulation of intercellular calcium levels and transport L-type amino acids. Alternatively spliced transcript variants, encoding different isoforms, have been characterized. Monocytes express high levels of CD98 antigen. Peripheral blood T- and B-cells, as well as NK-cells and granulocytes express low levels of CD98. Activation of T-cells and NK-cells leads to upregulation of CD98. RBCs are negative. IPO-T10 was typed at the VIth International Workshop and Conference on Human Leukocyte Differentiation Antigens. Positive control: Jurkat, MG63, HUT-78, K562, YT, U937 and human lymphocytes or tonsils.