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. Author manuscript; available in PMC: 2011 Apr 1.
Published in final edited form as: FEBS J. 2010 Mar 4;277(8):1832–1842. doi: 10.1111/j.1742-4658.2010.07609.x

Figure 5.

Figure 5

New model for the mechanism of multiple lysine methylation by the MLL1 core complex (adapted from [36]). a) The MLL1 core complex is composed of two distinct H3K4 methyltransferases each possessing H3K4 monomethylation activity on their own. The dashed oval on the WDR5-RbBP5-Ash2L-DPY-30 sub-complex indicates that the catalytic motif is presently unknown, and may be shared between subunits. b). WDR5’s recognition of the MLL1 Win motif results in the assembly of the MLL1 core complex, which possesses H3K4 dimethyltransferase activity. We suggest that the MLL1 SET domain catalyzes monomethylation of histone H3 at lysine 4, which is followed by transfer of the monomethylated histone H3 to a second active site on the WRAD sub-complex, where H3K4 dimethylation occurs. We propose that mechanisms that control the assembly of the MLL1 core complex will be important for the regulation of H3K4 methylation states in the cell.