Final answer:
MHC class I molecules typically handle peptides that are 8-10 amino acids in length, with the antigen-binding cleft formed by the α1 and α2 domains. Matching these MHC molecules plays a critical role in transplant compatibility.
Step-by-step explanation:
The peptide length that an MHC class I molecule can handle is typically 8-10 amino acids long. MHC class I molecules are composed of a larger α subunit and a smaller β2 microglobulin subunit. The antigen-binding cleft of MHC I, where peptides are loaded for presentation to T cells, is formed by the α1 and α2 domains. The peptides presented by MHC class I molecules are usually generated from proteins that originate inside the cell, signaling if the cell is healthy or infected with viruses or if it has become cancerous. Furthermore, matching MHC molecules is crucial in the context of transplants, as it determines the compatibility between donor and recipient and the transplant's success rate.