Untitled - D Ank Unlimited

CD4 molecule 141 CD8
CD4 molecule
Exists as a monomer and contains four immunogloblin-like
domains. The first domains form a rigid rod-like structure
linked to the two carboxyl terminal domains by a flexible
link. The binding site for major histocompatibility complex
(MHC) class II molecules is believed to involve the D 1 and
D 2 domains of CD4.
CD4 T cells
The T cell subset that expresses the CD4 coreceptor and
recognizes peptide antigens presented by major histocompatibility
complex (MHC) class II molecules.
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Structure of CD5.
CD5
Initially described as an alloantigen termed Ly-1 on murine
T cells. Subsequently, a pan T cell marker of similar molecular
mass was found on human lymphocytes using monoclonal
antibodies and named CD5. Thus, CD5 is homologous
at the DNA level with Ly-1. It is a 67-kDa type I transmembrane
glycoprotein comprised of a single polypeptide
of approximately 470 amino acids. The signal peptide is
formed by the first 25 amino acids. CD5 is expressed on the
surfaces of all αβ T cells but is absent or of low density on
γδ T cells. It has been discovered on many murine B cell
lymphomas and on endothelial cells of blood vessels in the
pregnant sheep uterus. CD72 on B cells is one of its three
ligands. CD5 is present on thymocytes and most peripheral
T cells. It is believed to be significant for the activation of
T cells and possibly B1 cells. CD5 is also present on a subpopulation
of B cells (B1 cells) that synthesize polyreactive
and autoreactive antibodies as well as the “natural antibodies”
present in normal serum. Human chronic lymphocytic
leukemia cells express CD5 which points to their derivation
from this particular B cell subpopulation.
CD5 B cells
An atypical, self-renewing class of B lymphocytes that
reside mainly in the peritoneal and pleural cavities in adults
and have far less diverse receptor repertoires than do conventional
B cells.
CD6
A molecule, sometimes referred to as the T12 antigen. It is a
single chain glycopolypeptide with a molecular weight of 105
kDa and is present on the majority of human T cells (similar
in distribution to CD3). It stains some B cells weakly.
CD7
An antigen (molecular weight of 40 kDa) that is present on
the majority of T cells and is useful as a marker for T cell
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neoplasms when other T cell antigens are absent. The CD7
antigen is probably an Fc receptor for immunoglobulin M
(IgM).
CD8
A cell surface glycoprotein on T cells that recognizes
antigens presented by major histocompatibility complex
(MHC) class I molecules. It binds to MHC class I molecules
on antigen-presenting cells and serves as a coreceptor to
facilitate the T cell response to antigen.
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Structure of CD8.
Ribbon structure of a human CD8 T cell receptor.
This structure consists of the N terminal 114 residues of CD8. These
residues make up a single immunoglobulin axis which coincides with a
crystallographic two-fold axis.
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