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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 works by mimicking the binding of CD4 to HIV, thereby preventing the virus from infecting T-helper cells. HIV infects T-helper cells by binding to the CD4 receptor and the co-receptor CCR5 or CXCR4. 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 ...
The antigen-presenting cells (APC) expose on their surface a fraction of the antigen that is recognized either from CD8+ T cells or CD4+ T cells. This binding leads to the activation of TCR signaling cascade in which the immunoreceptor tyrosine-based activation motifs (ITAM) located in the CD3-zeta chains (ζ-chains) of the TCR complex, are ...
The CD4 receptor in particular interacts with murine MHC-II following the "ball-on-stick" model, where the Phe-43 ball fits into the conserved hydrophobic α2 and β2 domain residues. [5] During binding with MHC-II, CD4 maintains independent structure and does not form any bonds with the TCR receptor.
The extracellular and transmembrane part of the coreceptor is from wild-type CD8 coreceptor, whereas the intracellular domain from CD4 coreceptor. [1] This model was created to examine role of coreceptor coupling to Lck (lymphocyte-specific protein tyrosine kinase) [1] as the CD4 and CD8 coreceptors have an Lck-binding site in their ...
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.
The motif contains a tyrosine separated from a leucine or isoleucine by any two other amino acids, giving the signature YxxL/I. [1] Two of these signatures are typically separated by between 6 and 8 amino acids in the cytoplasmic tail of the molecule (YxxL/Ix (6-8) YxxL/I). However, in various sources, this consensus sequence differs, mainly in ...
The Biopython project is an open-source collection of non-commercial Python tools for computational biology and bioinformatics, created by an international association of developers. [1] [4] [5] It contains classes to represent biological sequences and sequence annotations, and it is able to read