The CD160 molecule (BY55 antigen) is a 27-kDa  glycosyl phosphatidylinositol (GPI)-anchored glycoprotein of 181 amino acids  with a single immunoglobulin (Ig)-like domain The molecule contains two potential sites for N-glycosylation and is rich in cysteine (6 residues in the mature polypeptide)  indicating an important capacity for forming intra- and inter-chain disulfide bonds  which likely support the disulfide-linked multimeric (80 kDa) expression at the cell surface