In mouse small pre-B cells, the recruitment of the Rag1:Rag2 recombinase complex to the proper recombination sites within the Immunoglobulin kappa (Igk) locus is directed and enhanced by Brwd1. Brwd1 associates with the Igk locus through interaction with histone H3 acetylated at lysine residues K9 and K14 and phosphorylated at serine residue S10 (likely by ERK) (Mandal et al. 2015). Please note that the listed amino acid residues in mature histone H3 match nascent histone H3 residues K10, K15 and S11, respectively. Amino acid positions in Reactome annotations of modified residues and Reactome systematic names correspond to positions in the nascent protein UniProt sequence.