MHC class I molecules are one of two primary classes of major histocompatibility complex molecules and are found on the cell surface of all nucleated cells in the bodies of vertebrates. They also occur on platelets, but not on red blood cells.
MHC class I molecules (MHC-I) are cell surface recognition elements expressed on virtually all somatic cells. These molecules sample peptides generated within the cell and signal the cell's physiological state to effector cells of the immune system, both T lymphocytes and natural killer (NK) cells. In addition, molecules structurally related to MHC-I, collectively known as MHC-Ib, are more specialized and, in some cases, interact with more limited subsets of lymphoid cells. Using the recently determined structure of the classical MHC-I molecule, H-2Dd, as a paradigm for structure and function, we review other MHC-I and MHC-Ib molecules, with an emphasis on how the same basic structural fold is employed by classical MHC-I molecules to bind specific peptides and T cell receptors, and is exploited by the MHC-Ib molecules in more stringent molecular interactions. It is instructive that structurally related molecules have evolved to perform a number of unique and distinct functions in immune and non-immune recognition.
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MHC class I molecules are one of two primary classes of major histocompatibility complex molecules and are found on the cell surface of all nucleated cells in the bodies of vertebrates. They also occur on platelets, but not on red blood cells.
MHC class I molecules (MHC-I) are cell surface recognition elements expressed on virtually all somatic cells. These molecules sample peptides generated within the cell and signal the cell's physiological state to effector cells of the immune system, both T lymphocytes and natural killer (NK) cells. In addition, molecules structurally related to MHC-I, collectively known as MHC-Ib, are more specialized and, in some cases, interact with more limited subsets of lymphoid cells. Using the recently determined structure of the classical MHC-I molecule, H-2Dd, as a paradigm for structure and function, we review other MHC-I and MHC-Ib molecules, with an emphasis on how the same basic structural fold is employed by classical MHC-I molecules to bind specific peptides and T cell receptors, and is exploited by the MHC-Ib molecules in more stringent molecular interactions. It is instructive that structurally related molecules have evolved to perform a number of unique and distinct functions in immune and non-immune recognition.