Final answer:
The peptide-binding site of MHC Class I molecules is formed by the α1 and α2 domains.
Step-by-step explanation:
The domains α1 and α2 of MHC Class I molecules form the peptide-binding site. These molecules are essential components of the immune system, present on all nucleated body cells.
They play a crucial role in antigen processing and presentation. MHC Class I molecules present peptides from cytoplasm-derived proteins to T cells, enabling the immune system to recognize and defend against pathogens.
The peptide-binding cleft, formed by the α1 and α2 domains, is where antigenic peptides rest and are later recognized by T cell receptors. This process is vital for cellular immune responses against viruses and other intracellular pathogens.