| Modification of MBD 1 with either SUMO 2 / 3 or SUMO 1 facilitated the interaction between MBD 1 and MCAF 1 , suggesting that SUMOylation links the methylation of DNA and histones . ^^^ Specific knockdown of either SUMO 2 / 3 or SUMO 1 induced dissociation of MCAF 1 , trimethyl H 3 K9 , and the HP 1 proteins from the MBD 1 containing heterochromatin foci , suggesting a requirement for SUMOs for heterochromatin assembly . ^^^ |