MHC (Major Histocompatibility Complex) class I molecules are a type of protein complex found on the surface of all nucleated cells in vertebrates. They are also present on platelets but not on red blood cells. The main function of MHC class I molecules is to display peptide fragments of proteins from within the cell to cytotoxic T cells. This presentation triggers an immune response against non-self antigens displayed with the help of MHC class I proteins. MHC class I molecules are involved in the recognition and elimination of infected or abnormal cells by the immune system. In humans, the MHC class I molecules are encoded by the HLA-A, HLA-B, and HLA-C genes.
For more information, you can refer to the following sources:
- Wikipedia: https://en.wikipedia.org/wiki/MHC_class_I
- Khan Academy: https://www.khanacademy.org/science/biology/human-biology/immunology/v/mhc-i-and-mhc-ii-molecules