G9a and its interaction partner Glp1 methylate H1. (a) Candidate methylation assay on core nucleosomes and H1. Indicated HKMTs fused to GST (see also Methods) were used for methylation assays to identify enzymes methylating H1. Core nucleosomes (purified from HEK293) were mixed with H1 as substrates. All enzymes were tested in (lane 1) Tris, (lane 2) PBS, (lane 3) MAB and (lane 4) R methylation buffers. Incorporation of the methyl group from the donor adenosyl-L-methionine S-[methyl-3H] was detected by autoradiography (for a specificity control see Additional file 1). (b) Recombinantly expressed SET domains of Glp1 (610-917) and G9a (682-1000) and recombinant H1.2FL and H1.2CT were used for methylation assays. G9a and Glp1 methylate the H1.2 C-terminus (CT). Ponceau staining of the membrane (Pon, upper panels) and autoradiography (Rad, lower panel) are shown.