What enzyme complex is essential for V(D)J recombination and is encoded by RAG genes?

What enzyme complex is essential for V(D)J recombination and is encoded by RAG genes?

• A. RAG1/2 recombinases
• B. DNA polymerase delta
• C. TdT
• D. AID

Answer: (A)

The key driver of V(D)J recombination is the RAG1 and RAG2 recombinase complex. In developing B and T cells, this enzyme pair recognizes recombination signal sequences flanking V, D, and J gene segments and makes precise double-strand breaks to initiate rearrangement. This breaking and rejoining by the non-homologous end-joining machinery creates the diverse antigen receptor genes that underpin specificity. Other enzymes play different roles but not the initiators of this process. TdT adds nucleotides at the junctions to boost diversity after the breaks are made. AID acts in mature B cells to drive somatic hypermutation and class-switch recombination, not initial V(D)J rearrangement. DNA polymerase delta is involved in DNA replication and repair generally, not the initiating recombination event.

The key driver of V(D)J recombination is the RAG1 and RAG2 recombinase complex. In developing B and T cells, this enzyme pair recognizes recombination signal sequences flanking V, D, and J gene segments and makes precise double-strand breaks to initiate rearrangement. This breaking and rejoining by the non-homologous end-joining machinery creates the diverse antigen receptor genes that underpin specificity.

Other enzymes play different roles but not the initiators of this process. TdT adds nucleotides at the junctions to boost diversity after the breaks are made. AID acts in mature B cells to drive somatic hypermutation and class-switch recombination, not initial V(D)J rearrangement. DNA polymerase delta is involved in DNA replication and repair generally, not the initiating recombination event.