Figure 5.

Structural comparison of various HDAC complexes. A, crystal structure of the MTA1–InsP₆–HDAC1 complex (PDB code 5ICN). B, structural model of the SAP30 ZnF–InsP₆–HDAC1 complex from molecular docking. C, crystal structure of the SMRT DAD–InsP₄–HDAC3 complex (PDB code 4A69). Note the parallels in InsP and HDAC engagement by the MTA1 and SMRT subunits featuring structurally similar SANT domains, whereas the mode of InsP and HDAC engagement by the structurally unrelated SAP30 ZnF domain is unique, implying convergent evolution at the functional level.