Here's why:
* Function: MHC class I proteins present fragments of proteins (peptides) found inside the cell to cytotoxic T lymphocytes (CTLs). This allows the CTLs to recognize and destroy cells that are infected with viruses or other pathogens, or that are cancerous.
* Importance: This function is critical for the immune system to identify and eliminate threats within the body.
* Exceptions: There are a few cell types that do not express MHC class I proteins, such as red blood cells and neurons. However, the vast majority of cells in the body do express MHC class I.
Let me know if you have any other questions about MHC proteins!
