Kaiso, a new protein of the BTB/POZ family, specifically binds to methylated DNA sequences

A protein specifically binding to a symmetrically methylated DNA fragment o f the first intron of the mts1 gene was studied. The protein was purified b y gel filtration and affinity chromatography. Mass spectrometry showed that the protein is Kaiso, a new member of the BTB/POZ family. To study the ass ociation with methylated DNA sequences in vivo, the location of Kaiso in NI H 3T3 cells was analyzed. Immunofluorescent staining with polyclonal antibo dies against Kaiso showed that the protein is predominantly associated with the nucleoli. The causes of its distribution awaits further investigation. The zinc-finger domains of Kaiso were for the first time demonstrated to s pecifically recognize symmetrically methylated DNA sequences in vitro.