Genomic imprinting in mammals - an interplay between chromatin and DNA methylation?

Most imprinted loci have key regulatory elements that are methylated on onl y one of the parental chromosomes. For several of these 'differentially met hylated regions', recent studies establish that the unmethylated chromosome has a specialized chromatin organization that is characterized by nuclease hypersensitivity. The novel data raise the question of whether specific pr oteins and associated chromatin features regulate the allele-specificity of DNA methylation at these imprinting control elements.