Figure 3.

mtA HMGB1, but not mtB HMGB1, stimulates RAG-mediated 23-RSS hairpin formation in Mg²⁺, but both proteins promote cleavage under conditions favouring synapsis in Mg²⁺ and in reactions containing Mn²⁺. (A-B) In vitro cleavage reactions were performed as in Fig. 2, except that mtA HMGB1 and mtB HMGB1 replaced HMG-box A and HMG-box B in the cleavage reactions.