Which MHC complex is expressed on all nucleated cells, and what does it bind?

Which MHC complex is expressed on all nucleated cells, and what does it bind?

• A. MHC-I; binds TCR and CD8
• B. MHC-II; binds TCR and CD4
• C. MHC-I; binds BCR
• D. MHC-II; binds CD8

Answer: (A)

MHC class I molecules are present on every nucleated cell to survey intracellular proteins and present endogenous peptide fragments to CD8+ cytotoxic T cells. The T cell receptor recognizes the peptide-MHC I complex, with the CD8 co-receptor binding to MHC I and stabilizing the interaction. This is different from MHC class II, which sits on professional antigen-presenting cells and presents exogenous peptides to CD4+ helper T cells via the CD4 co-receptor. The B cell receptor is not a binding partner for MHC molecules. So, MHC I binds TCR and CD8, confirming why this pairing fits the description.

MHC class I molecules are present on every nucleated cell to survey intracellular proteins and present endogenous peptide fragments to CD8+ cytotoxic T cells. The T cell receptor recognizes the peptide-MHC I complex, with the CD8 co-receptor binding to MHC I and stabilizing the interaction. This is different from MHC class II, which sits on professional antigen-presenting cells and presents exogenous peptides to CD4+ helper T cells via the CD4 co-receptor. The B cell receptor is not a binding partner for MHC molecules. So, MHC I binds TCR and CD8, confirming why this pairing fits the description.