Figure 2. SMYD3 preferentially catalyzes histone 4 lysine methylation in vitro.
(A, B) SMYD3 purified from baculovirus methylates all histones (H4>>H2A>H3>H2B) in vitro. Histone methyltransferase (HMTase) assays employed mixed histones from HeLa cells as substrate. Upper panel, fluorography showing 3H-incorporation into H3 (17 kD) and into species smaller bands (H2A/H2B and H4). Lower panel, Coomassie-stained SDS-PAGE gel used to verify equal loading. (C) SMYD3 purified from bacteria methylates histones H4>>H3>H2A in vitro. Recombinant histones or mixed histones were used, as indicated, for substrate. Fluorography is shown and the bands corresponding to each histone are indicated.