Three clustered YY1 binding sites located in the Xist/Tsix and Nespas loci. (A) The genomic structure of the Xist/Tsix locus. The arrows indicate the direction of Xist and Tsix transcription, and each gene has two different transcription start sites. The arrowheads indicate the positions of two clustered YY1 binding sites. (B,C) The conservation patterns of two clustered YY1 binding sites, the Xist cluster and the Tsix cluster. The two divergent motifs found in the Tsix clusters are marked: one with an underline and the other without an underline. (D) The genomic structure of the Gnas-imprinted domain and the conservation patterns of the clustered YY1 binding site located in the first intron of Nespas. The nucleotide bases are in boldface type if the sequences of each binding motif are identical to the consensus sequence of known YY1 binding sites.
