 Each motif is flanked by a 7 bp and 9 bp sequence that is separated by a 12 bp spacer, referred to as class 1, or a 23 bp spacer, referred to as class 2.A recombinase made up of RAG1 and RAG2 subunits always cleave between these two sites.The cleavage results in two hairpin structures for the V and J segments, respectively, and the non-coding region, are now separated from the V and J segments by a DSB.