Co-receptor: Difference between revisions

Latest revision as of 11:45, 15 February 2025

Co-receptor[edit]

Diagram of T-cell receptor and MHC interaction

A co-receptor is a cell surface receptor that binds a signaling molecule in addition to a primary receptor in order to facilitate ligand recognition and initiate a biological response. Co-receptors are crucial in the immune system, particularly in the function of T cells and their interaction with antigens.

Function[edit]

Co-receptors play a significant role in enhancing the sensitivity and specificity of the primary receptor. In the context of the immune system, co-receptors are involved in the recognition of antigens presented by major histocompatibility complex (MHC) molecules. The most well-known co-receptors are CD4 and CD8, which are expressed on the surface of T cells.

CD4 and CD8[edit]

T-cell receptor complex with CD4 and CD8 co-receptors

CD4 and CD8 are glycoproteins that serve as co-receptors for the T-cell receptor (TCR). CD4 is primarily expressed on helper T cells and interacts with MHC class II molecules, while CD8 is found on cytotoxic T cells and interacts with MHC class I molecules. These interactions are crucial for the activation and differentiation of T cells.

Mechanism[edit]

The co-receptor binds to a specific part of the MHC molecule, stabilizing the interaction between the TCR and the antigen-MHC complex. This stabilization enhances the signal transduction pathways that lead to T cell activation. The presence of co-receptors lowers the threshold for T cell activation, allowing for a more robust immune response.

Importance in Immunology[edit]

Co-receptors are essential for the proper functioning of the immune system. They ensure that T cells are activated only when they encounter the correct antigen-MHC complex, preventing inappropriate immune responses. This specificity is vital for maintaining self-tolerance and preventing autoimmune diseases.

Related pages[edit]

@@ Line 1: / Line 1: @@
-'''Co-receptor'''
+== Co-receptor ==
-A '''[[Co-receptor]]''' is a cell surface receptor that binds a signalling molecule in addition to a primary receptor in order to facilitate ligand recognition and initiate biological processes, such as entry of a pathogen into a host cell.
+[[File:063-T-CellReceptor-MHC.tiff|thumb|right|Diagram of T-cell receptor and MHC interaction]]
+A '''co-receptor''' is a cell surface receptor that binds a signaling molecule in addition to a primary receptor in order to facilitate ligand recognition and initiate a biological response. Co-receptors are crucial in the immune system, particularly in the function of [[T cells]] and their interaction with [[antigens]].
 == Function ==
-Co-receptors are not directly involved in signal transduction but they assist the primary receptor, often by holding the ligand in place or by facilitating interaction between the ligand and the primary receptor. They can also affect the duration or intensity of the primary receptor's signal.
+Co-receptors play a significant role in enhancing the sensitivity and specificity of the primary receptor. In the context of the immune system, co-receptors are involved in the recognition of [[antigen]]s presented by [[major histocompatibility complex]] (MHC) molecules. The most well-known co-receptors are [[CD4]] and [[CD8]], which are expressed on the surface of T cells.
-== Types of Co-receptors ==
-There are several types of co-receptors, including:
+=== CD4 and CD8 ===
-* '''[[CD4]]''' and '''[[CD8]]''': These are co-receptors for the T cell receptor. CD4 binds to MHC class II molecules and CD8 binds to MHC class I molecules.
+[[File:063-T-CellReceptor-MHC.tiff|thumb|left|T-cell receptor complex with CD4 and CD8 co-receptors]]
-* '''[[CCR5]]''' and '''[[CXCR4]]''': These are co-receptors for HIV entry into host cells.
-* '''[[CD28]]''' and '''[[CTLA-4]]''': These are co-receptors for the B7 family of costimulatory molecules.
-== Role in Disease ==
+CD4 and CD8 are glycoproteins that serve as co-receptors for the T-cell receptor (TCR). CD4 is primarily expressed on [[helper T cells]] and interacts with MHC class II molecules, while CD8 is found on [[cytotoxic T cells]] and interacts with MHC class I molecules. These interactions are crucial for the activation and differentiation of T cells.
-Co-receptors play a crucial role in the pathogenesis of several diseases. For example, the CCR5 and CXCR4 co-receptors are exploited by HIV to gain entry into host cells. Mutations in these co-receptors can affect susceptibility to HIV infection.
+== Mechanism ==
-== See Also ==
+The co-receptor binds to a specific part of the MHC molecule, stabilizing the interaction between the TCR and the antigen-MHC complex. This stabilization enhances the signal transduction pathways that lead to T cell activation. The presence of co-receptors lowers the threshold for T cell activation, allowing for a more robust immune response.
-* [[Receptor (biochemistry)]]
+== Importance in Immunology ==
-* [[Signal transduction]]
-* [[Ligand (biochemistry)]]
-== References ==
+Co-receptors are essential for the proper functioning of the immune system. They ensure that T cells are activated only when they encounter the correct antigen-MHC complex, preventing inappropriate immune responses. This specificity is vital for maintaining self-tolerance and preventing [[autoimmune disease]]s.
-<references />
+== Related pages ==
-{{stub}}
+* [[T cell receptor]]
+* [[Major histocompatibility complex]]
+* [[CD4]]
+* [[CD8]]
+* [[Antigen presentation]]
-[[Category:Cell biology]]
 [[Category:Immunology]]
-[[Category:Receptors]]