Fig. (3) CTD-mediated auto-inhibition. The CTD domain of SMYD1 and 3 is connected via a hinge to the core structure, and may control enzymatic activity by opening or closing the substrate binding site. The left panel is a composite image of the SMYD1 structure with a co-crystallized H3K4 peptide from a superimposed SETD7 structure (PDB code 1o9s).