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Locus Suicide Recombination
Locus suicide recombination (LSR) constitutes a variant form of class switch recombination that eliminates all immunoglobulin heavy chain constant genes. It thus terminates immunoglobulin and B-cell receptor The B cell receptor (BCR) is a transmembrane protein on the surface of a B cell. A B cell receptor is composed of a membrane-bound immunoglobulin molecule and a signal transduction moiety. The former forms a type 1 transmembrane receptor protein, ... (BCR) expression in B-lymphocytes and results in B-cell death since survival of such cells requires BCR expression. This process is initiated by the enzyme activation-induced deaminase upon B-cell activation. LSR is thus one of the pathways that can result into activation-induced cell death in the B-cell lineage.{{cite journal , last=Peron , first=S. , last2=Laffleur , first2=B. , last3=Denis-Lagache , first3=N. , last4=Cook-Moreau , first4=J. , last5=Tinguely , first5=A. , last6=Delpy , first6=L. , last7=Denizot , ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Class Switch
Immunoglobulin class switching, also known as isotype switching, isotypic commutation or class-switch recombination (CSR), is a biological mechanism that changes a B cell's production of immunoglobulin from one type to another, such as from the isotype IgM to the isotype IgG. During this process, the constant-region portion of the antibody heavy chain is changed, but the variable region of the heavy chain stays the same (the terms ''variable'' and ''constant'' refer to changes or lack thereof between antibodies that target different epitopes). Since the variable region does not change, class switching does not affect antigen specificity. Instead, the antibody retains affinity for the same antigens, but can interact with different effector molecules. Mechanism Class switching occurs after activation of a mature B cell via its membrane-bound antibody molecule (or B cell receptor) to generate the different classes of antibody, all with the same variable domains as the origin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Immunoglobulin
An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the pathogen, called an antigen. Each tip of the "Y" of an antibody contains a paratope (analogous to a lock) that is specific for one particular epitope (analogous to a key) on an antigen, allowing these two structures to bind together with precision. Using this binding mechanism, an antibody can ''tag'' a microbe or an infected cell for attack by other parts of the immune system, or can neutralize it directly (for example, by blocking a part of a virus that is essential for its invasion). To allow the immune system to recognize millions of different antigens, the antigen-binding sites at both tips of the antibody come in an equally wide variety. In contrast, the remainder of the antibody is relatively constant. It only occurs in a few va ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
B-cell Receptor
The B cell receptor (BCR) is a transmembrane protein on the surface of a B cell. A B cell receptor is composed of a membrane-bound immunoglobulin molecule and a signal transduction moiety. The former forms a type 1 transmembrane receptor protein, and is typically located on the outer surface of these lymphocyte cells. Through biochemical signaling and by physically acquiring antigens from the immune synapses, the BCR controls the activation of the B cell. B cells are able to gather and grab antigens by engaging biochemical modules for receptor clustering, cell spreading, generation of pulling forces, and receptor transport, which eventually culminates in endocytosis and antigen presentation. B cells' mechanical activity adheres to a pattern of negative and positive feedbacks that regulate the quantity of removed antigen by manipulating the dynamic of BCR–antigen bonds directly. Particularly, grouping and spreading increase the relation of antigen with BCR, thereby proving sensit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AICDA
Activation-induced cytidine deaminase, also known as AICDA, AID and single-stranded DNA cytosine deaminase, is a 24 kDa enzyme which in humans is encoded by the ''AICDA'' gene. It creates mutations in DNA by deamination of cytosine base, which turns it into uracil (which is recognized as a thymine). In other words, it changes a C:G base pair into a U:G mismatch. The cell's DNA replication machinery recognizes the U as a T, and hence C:G is converted to a T:A base pair. During germinal center development of B lymphocytes, AID also generates other types of mutations, such as C:G to A:T. The mechanism by which these other mutations are created is not well understood. It is a member of the APOBEC family. In B cells in the lymph nodes, AID causes mutations that produce antibody diversity, but that same mutation process leads to B cell lymphoma. Function This gene encodes a DNA-editing deaminase that is a member of the cytidine deaminase family. The protein is involved in somati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Activation-induced Cell Death
AICD (activation-induced cell death) is programmed cell death caused by the interaction of Fas receptors (Fas, CD95) and Fas ligands (FasL, CD95 ligand).Zhang J, Xu X, Liu Y. (2004), Activation-Induced Cell Death in T Cells and Autoimmunity. Cell Mol Immunol. 1(3):186-92 AICD is a negative regulator of activated T lymphocytes that results from repeated stimulation of their T-cell receptors (TCR) and helps to maintain peripheral immune tolerance. Alteration of the process may lead to autoimmune diseases. The AICD effector cell is one that expresses FasL, and apoptosis is induced in the cell expressing the Fas receptor. Both activated T cells and B cells express Fas and undergo clonal deletion by the AICD mechanism.Green DR, Droin N, Pinkoski M. (2003), Activation-induced cell death in T cells. Immunol Rev. 193:70-81 Activated T cells that express both Fas and FasL may be killed by themselves or by each other. Signaling The binding of Fas ligand to Fas receptor triggers trimeri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
