Final answer:
Processed peptides are presented in the peptide-binding cleft of MHC molecules on the surface of antigen-presenting cells, facilitating their recognition by T cells. MHC molecules are capable of presenting a wide range of antigenic peptides. Post-translational modifications are crucial for the polypeptide to become a functional protein.
Step-by-step explanation:
After a peptide is processed within a cell, it associates with major histocompatibility complex (MHC) molecules for antigen presentation. The peptide-binding cleft of an MHC molecule, which is located at one end of the MHC furthest from the cell membrane, receives the processed peptide. This peptide-MHC complex is then presented on the cell surface where it can be recognized by T cell receptors. Incorporating various amino acid sequences, MHC molecules have the ability to present a diverse range of antigens within their peptide-binding clefts. The antigen-presenting cells play a crucial role in this process by internalizing antigens, processing them into smaller fragments, and presenting them on their surface with MHC molecules, facilitating T cell recognition and response.
The broader context involves the synthesis and modification of polypeptides. After translation, a polypeptide undergoes folding and may bind with other molecules or polypeptides. Post-translational modifications in the Golgi apparatus are essential for the protein to become fully functional and execute its specific roles within the cell.