Slow egress of a mouse MHC class I molecule to the cell surface despite its strong association with beta sub(2)-microglobulin

Two H-2D region class I genes from the wild-derived mouse strain B10.GAA37 provisionally encoding the D super(w16) and L super(w16) molecules, respectively, were transfected into mouse L cells, and the expressed gene products were analyzed serologically by flow cytometry. As expected from nucleotide sequence comparisons, these analyses revealed that several L super(d)-reactive monoclonal antibodies (mAbs) recognize L super(w16) and not D super(w16). Together, these studies indicate that the slower trafficking of L super(w16) to the surface does not result from a weaker association with beta sub(2)-m, suggesting that other factors, such as peptide ligand-induced assembly, and/or retention by ER-resident proteins play an important role in the trafficking of major histocompatibility (MHC) class I molecules to the cell surface.