CHRomatin Organization Modifier (chromo) domain of insect HP1a. HP1a is a member of the heterochromatin protein family, and is enriched in the heterochromatin and associated with centromeres. HP1 has diverse functions in heterochromatin formation and impacts both gene expression and gene silencing. HP1 has two conserved protein-protein interaction domains, a single N-terminal chromodomain (CD) which can bind to histone proteins via methylated lysine residues, and a related C-terminal chromo shadow domain (CSD) which is responsible for the homodimerization and interaction with a number of chromatin-associated non-histone proteins; a flexible hinge region separates the CD and CSD and may bind nucleic acid. HP1 is a highly conserved non-histone chromosomal protein that is evolutionarily conserved from fission yeast to plants and animals. In Drosophila, there are at least five HP1 family proteins, this subgroup includes the CD of Drosophila melanogaster HP1a.
Jiyao W et al.(2023). "The conserved domain database in 2023.",