Mammalian DNA cytosine-5 methyltransferase interacts with p23 protein

In higher eukaryotic genomes, methylated cytosine residues (m(5)C) are distributed in heritable, cell-type-specific patterns, which are believed to be involved in the control of gene expression, developmental regulation and genomic imprinting. These methylation patterns are established and maintained by DNA cytosine-5 methyltransferase (MTase), a approximately 1500 amino acid enzyme containing a regulatory N-terminal domain and a catalytic C-terminal domain. The mechanism responsible for targeting MTase to particular genes is poorly understood and might possibly involve interactions with other proteins. In an effort to identify proteins that interact with the mammalian MTase, we used the yeast two-hybrid system with several different MTase domains as baits. Here we report an interaction between the C-terminal catalytic domain of the MTase and p23, a protein previously reported to associate with the progesterone receptor (PR) complex.