Popis: |
Transcription in organisms as diverse as yeast and mammals is subject to chromosomal position effects that result in heritable and variegated patterns of gene expression. Two recent studies have employed a reversible protein-DNA crosslinking method to identify the structural components of heterochromatin in budding yeast(1,2). The results show that a complex containing the proteins Rap1, Sir2p, Sir3p and Sir4p is physically associated with nucleosomes at telomere proximal regions, but that the repressive chromatin structure extended by Sir3p overexpression has a different composition. |