What does RAG1 and RAG2 do?
The RAG1 and RAG2 proteins initiate V(D)J recombination by introducing double-strand breaks at the border between a recombination signal sequence (RSS) and a coding segment.
Where exactly does the RAG1 2 Complex introduce a single-strand break into the DNA during somatic rearrangement?
RAG1 and RAG2 initiate recombination by introducing a single-strand nick in DNA precisely at the border between the heptamer of RSS and the coding segment.
Where does RAG cleave DNA?
The RAG-1 core contains three acidic residues (D600, D708, and E962) in what is called the DDE motif, the major active site for DNA cleavage. These residues are critical for nicking the DNA strand and for forming the DNA hairpin.
What does Vdj recombination produce?
VDJ recombination is the process by which T cells and B cells randomly assemble different gene segments – known as variable (V), diversity (D) and joining (J) genes – in order to generate unique receptors (known as antigen receptors) that can collectively recognize many different types of molecule.
What is the significance of RAG1 2 in B cell development?
Recombination activating gene 1 and 2 (RAG1/2) are essential in initiating the V(D)J recombination that diversifies the T- and B-cell repertoire. Therefore complete RAG deficiency results in T− B− NK+ SCID phenotype.
Where does the RAG complex cut the Dsdna?
During the process of V(D)J recombination, the RAG complex brings two signal sequences together (synapsis) and cleaves them at the 5′ end of the heptamer at its junction with the V, D, or J coding end (9, 10).
How many V genes do humans have?
In humans, there are approximately 50 known functional V (variable) segments [3-6], 27 known functional D (diversity) segments [3,7,8], and six known functional J (joining) segments [3,8,9] available within a single locus for assembly into heavy chain genes.
Where are Rag genes expressed?
Recombination activating genes (RAG)1 and RAG2 are expressed in developing B and T lymphocytes and are required for the rearrangement of antigen receptor genes. In turn, RAG expression is regulated by the products of these assembled immunoglobulin (Ig) and T-cell receptor (TCR) genes.
What is the difference between RAG1 and RAG2?
Unlike the binding of RAG1 plus RAG2, RAG1 can bind to DNA in the absence of a divalent metal ion and does not require the presence of coding flank sequence. Conversely, the heptamer is rendered more accessible to chemical attack, suggesting that binding of RAG1 plus RAG2 distorts the DNA near the coding/signal border.
Which pathway joins the DNA ends created by RAG1 RAG2 cleavage during VDJ recombination?
The frequent presence of such “microscopic” junctional alterations at coding joints provides a powerful mechanism for amplifying the diversity of antigen binding sites in T cell receptor and immunoglobulin molecules. RAG-generated DNA ends are normally joined by cNHEJ (reviewed by (51).
How does VDJ recombination contribute to antibody diversity?
The V(D)J recombination that occurs during B-cell development, along with somatic mutation after antigenic stimulation, leads to the generation of antigen-binding diversity.