Structure and function of a membrane-bound murine MHC class I molecule.
MHC molecules are expressed at the surface of nucleated cells to present peptides to T cells. Structural information on MHC molecules has been gathered by x-ray crystallography techniques by using soluble proteins. Although relationships between MHC molecules and cell membranes have not been studied in detail, they are of critical importance for T cell recognition. Using a chemically modified lipid, we have been able to capture and orient histidine-tagged MHC molecules on lipid membranes. Surface plasmon resonance experiments show that the protein binds to the nickel lipid in a specific manner and in an oriented fashion, which allows T cell receptor binding. Similar lipid surfaces have been used to grow two-dimensional crystals and to determine the structure of a membrane-anchored murine H-2Kb MHC class I molecule. The docking of the crystallographic structure into the three-dimensional reconstructed structure derived from the two-dimensional crystals allows us to determine that the histidine tag is near the membrane surface and that the MHC molecule is in an upright position, exposing the peptide/alpha1-alpha2 domains toward the T cell.
D000818:Animals; D003460:Crystallization; D018360:Crystallography, X-Ray; D004058:Diffusion; D006183:H-2 Antigens / Q000737:chemistry / Q000276:immunology; D006639:Histidine / Q000737:chemistry; D015395:Histocompatibility Antigens Class I / Q000737:chemistry* / Q000276:immunology; D008055:Lipids / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry* / Q000648:ultrastructure; D008565:Membrane Proteins / Q000737:chemistry*; D051379:Mice; D008854:Microscopy, Electron; D008958:Models, Molecular; D015394:Molecular Structure; D020349:Surface Plasmon Resonance