Final answer:
The introduction of a transient hairpin that links the two strands in the V(D)J coding regions is mediated by the RAG-1/2 proteins.
Step-by-step explanation:
The introduction of a transient hairpin that links the two strands in the V(D)J coding regions is mediated by the RAG-1/2 proteins. The RAG-1/2 proteins, also known as recombination activating gene proteins, are responsible for the rearrangement of the variable (V), diversity (D), and joining (J) segments in the genes that code for immunoglobulins or T-cell receptors.
These proteins recognize and bind to specific recombination signal sequences (RSS) flanking the V, D, and J segments, and catalyze the formation of DNA double-strand breaks, resulting in the formation of hairpin structures that join the segments together during the process of V(D)J recombination.