(Proceedings of the National Academy of Sciences, 2002) Boyson, J. E.; Erskine, R.; Whitman, Mary; Chiu, Michael; Lau, J. M.; Koopman, L. A.; Valter, M. M.; Angelisova, P.; Horejsi, V.; Strominger, Jack
HLA-G is a nonclassical class I MHC molecule with an unknown function and with unusual characteristics that distinguish it from other class I MHC molecules. Here, we demonstrate that HLA-G forms disulfide-linked dimers that are present on the cell surface. Immunoprecipitation of HLA-G from surface biotinylated transfec- tants using the anti-[]2-microglobulin mAb BBM.1 revealed the presence of an []78-kDa form of HLA-G heavy chain that was reduced by using DTT to a 39-kDa form. Mutation of Cys-42 to a serine completely abrogated dimerization of HLA-G, suggesting that the disulfide linkage formed exclusively through this residue. A possible interaction between the HLA-G monomer or dimer and the KIR2DL4 receptor was also investigated, but no interaction between these molecules could be detected through several approaches. The cell-surface expression of dimerized HLA-G molecules may have implications for HLA-G[]receptor interactions and for the search for specific receptors that bind HLA-G.
