V(D)J recombination-activating protein 2 (RAG2)

Core part of the RAG complex, a multiprotein complex that mediates the DNA cleavage stage during V(D)J recombination. DNA cleavage by the RAG complex occurs in two steps: a first nick is introduced in the top strand immediately upstream of the heptamer, generating a 3'-hydroxyl group that can attack the phosphodiester bond on the opposite strand in a direct transesterification reaction, thereby generating 4 DNA ends: two hairpin coding ends and two blunt, 5'-phosphorylated ends.

The chromatin structure plays a vital role in the V(D)J recombination reactions and the presence of histone H3 trimethylated at'Lys-4' (H3K4me3) stimulates both the nicking and haipinning steps. The RAG complex also plays a role in pre-B mobile allelic exclusion, a procedure leading to expression of a single immunoglobulin heavy chain allele to apply clonality and monospecific recognition by the B- cell antigen receptor (BCR) expressed on human B-lymphocytes.