MHC Class I Molecules in Antigen Presentation to Immune System

Can two very similar MHC class I molecules present the same virus peptide to a cell?

No, two very similar Major Histocompatibility Complex (MHC) class I molecules cannot present the same virus peptide to a cell. This is because the MHC class I molecules have a crucial role in presenting antigenic peptides derived from intracellular pathogens, such as viruses, to the immune system.

MHC class I molecules are cell surface proteins that are found on virtually all nucleated cells in the body. They play a crucial role in the immune response by presenting antigenic peptides to CD8+ T cells. These peptides are typically derived from intracellular pathogens that have infected the host cell. When a cell is infected by a virus, viral proteins are broken down into small peptides by a process called proteolysis. These peptides then bind to the MHC class I molecules in the endoplasmic reticulum

The binding of peptides to MHC class I molecules is governed by specific amino acid residues within the binding groove of the MHC molecule. These residues form anchor points that interact with specific amino acids in the peptide. The binding specificity of MHC class I molecules ensures that only antigenic peptides that have a high affinity for the MHC molecule will be presented to CD8+ T cells

While two MHC class I molecules may be very similar in structure, they will have subtle differences in the amino acid residues within their binding groove. These differences ultimately determine the peptides that can bind to each MHC molecule. Thus, even if two MHC class I molecules are structurally similar, they will present different antigenic peptides to the immune system. This diversity in antigen presentation is crucial for the immune system’s ability to recognize and respond to a wide range of pathogens

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