| Transcriptional repression and heterochromatin formation by MBD 1 and MCAF / AM family proteins . ^^^ Here we show that MBD 1 containing chromatin associated factor ( MCAF ) 1 , also known as the human homologue of murine ATFa associated modulator ( AM ) , is required for transcriptional repression and heterochromatin formation by MBD 1 , together with the involvement of SETDB 1 . ^^^ Immunoprecipitation and in vitro binding analyses reveal that both MCAF proteins interact with MBD 1 , SETDB 1 , and Sp 1 via two evolutionarily conserved distinct domains . ^^^ Furthermore , MCAF 1 enhances transcriptional repression by MBD 1 together with SETDB 1 , and exogenous expression of MCAF 2 partly compensates for the repressive activity in MCAF 1 knockdown HeLa cells . ^^^ The expression of MBD 1 mutant , which lacks interaction with MCAF proteins , perturbs heterochromatin protein 1 enriched heterochromatin formation at the MBD 1 containing chromosomal loci . ^^^ |