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Image of CD4 co-receptor binding to MHC (Major Histocompatibility Complex) non-polymorphic region. In molecular biology, CD4 (cluster of differentiation 4) is a glycoprotein that serves as a co-receptor for the T-cell receptor (TCR). CD4 is found on the surface of immune cells such as helper T cells, monocytes, macrophages, and dendritic cells.
CD4-Ig binds to the viral envelope glycoprotein gp120, which is responsible for HIV binding to CD4. By binding to gp120, CD4-Ig prevents the virus from binding to the CD4 receptor on T-helper cells, thus preventing infection. [11] CD4-Ig has also been investigated as a potential treatment for other diseases that involve immune dysregulation ...
The binding of the antigen-MHC to the TCR complex and CD4 may also help the APC and the T h cell adhere during T h cell activation, but the integrin protein LFA-1 on the T cell and ICAM on the APC are the primary molecules of adhesion in this cell interaction. [citation needed]
Boehme et al. demonstrated this interesting dual outcome by blocking the binding of CD4 to MHC-II which prevented the programmed cell death reaction that active T-cells typically display. [6] The CD4 receptor is composed of four concatamerized Ig-like domains and is anchored to the cell membrane by a single transmembrane domain.
Human immunodeficiency virus binds CD4 and a chemokine receptor on the surface of a T helper cell to gain entry. The number of CD4 and CD8 T cells in blood is often used to monitor the progression of HIV infection. [citation needed]
Interaction of TCR and co-receptors CD4 and CD8 with MHC molecules. During positive selection, co-receptors CD4 and CD8 initiate a signaling cascade following MHC binding. [19] This involves the recruitment of Lck, a tyrosine kinase essential for T cell maturation that is associated with the cytoplasmic tail of the CD4 or CD8 co-receptors.
Successful binding of the antigen receptor to the epitope, if accompanied by additional signals, results in: Stimulation of the cell to leave G 0 and enter the cell cycle . Repeated mitosis leads to the development of a clone of cells bearing the same antigen receptor; that is, a clone of cells of the identical specificity.
Antigen processing and presentation in MHC-I pathway. Cytotoxic T cells (also known as T c, killer T cell, or cytotoxic T-lymphocyte (CTL)) express CD8 co-receptors and are a population of T cells that are specialized for inducing programmed cell death of other cells.