Chromatin Higher Order Structure and Chromosomal Positioning in the Nucleus

While it has been known for some time that chromatin is highly packaged, it has only recently been discovered that chromatin is attached to the nuclear matrix. It has also been recently shown that interphase chromosomes remain separate from one another in so called, “chromosome domains.” This author suggests a functional relationship between chromatin attachment to the nuclear matrix and chromosomal domains in the interphase nucleus. Herein, the evidence for the presence of matrix attachment sites and chromosomal domains is presented, and it is proposed that chromatin attachment to the nuclear matrix provides the physical foundation for interphase chromosomes to be localized to chromosome domains.