Fig. 1
From: Functions of HP1 proteins in transcriptional regulation
Structure of HP1 orthologs and related proteins. To be classified as a full-length HP1 family member, a gene must code for a chromodomain (CD), a chromoshadow domain (CSD), and a hinge region. The CD mediates binding to methylated lysine residues on histone tails and in other proteins. The CSD mediates formation of homo- and heterodimers. Examples of full-length HP1 proteins include HP1a in D. melanogaster, Swi6 in S. pombe, and LHP1 in A. thaliana. Partial duplications of HP1 protein encoding genes result in descendant genes that contain either only a CD (such as D. melanogaster Oxpecker) or only a CSD (such as D. melanogaster Umbrea). Typically, the proteins derived from these partial duplications are classified as “HP1-like” [11]