InterPro domain: IPR017984

The CHROMO (CHRromatin Organization MOdifier) domain [ 1 , 2 , 3 , 4 ] is a conserved region of around 60 amino acids, originally identified in Drosophila modifiers of variegation.These are proteins that alter the structure of chromatin to the condensed morphology of heterochromatin, a cytologically visible condition where gene expression is repressed. In one of these proteins, Polycomb, the chromo domain has been shown to be important for chromatin targeting. Proteins that contain a chromo domain appear to fall into 3 classes. The first class includes proteins having an N-terminal chromo domain followed by a region termed the chromo shadow domain [ 5 ], eg. Drosophila and human heterochromatin protein Su(var)205 (HP1). The second class includes proteins with a single chromo domain, eg. Drosophila protein Polycomb (Pc); mammalian modifier 3; human Mi-2 autoantigenand and several yeast and Caenorhabditis elegans hypothetical proteins. In the third class paired tandem chromo domains are found, eg. in mammalian DNA-binding/helicase proteins CHD-1 to CHD-4 and yeast protein CHD1.

This entry represents a subgroup of the Chromo domain

1. Imprinting a determined state into the chromatin of Drosophila. Trends Genet. 6, 416-21
2. A sequence motif found in a Drosophila heterochromatin protein is conserved in animals and plants. Nucleic Acids Res. 19, 789-94
3. The chromo shadow domain, a second chromo domain in heterochromatin-binding protein 1, HP1. Nucleic Acids Res. 23, 3168-73
4. The chromo superfamily: new members, duplication of the chromo domain and possible role in delivering transcription regulators to chromatin. Nucleic Acids Res. 23, 4229-33