LIG_HP1_1

HP1 is a nonhistone chromosomal protein primarily associated with heterochromatin. In mammals three variants exist: HP1 alpha, HP1 beta and HP1 gamma. All have an N-terminal chromodomain (SM00298) and a C-terminal chromoshadow domain (SM00300). The HP1 chromodomain can bind to metylated lysine 9 on histone H3, while the chromoshadow domain can mediate homo-dimerisation and interaction with other proteins. The PxVxL motif was identified as a HP1-binding motif by Smothers,2000). Several chromatin modifying proteins have been shown to interact with HP1 using this motif. Structural analysis has shown that the motif interacts with a chomoshadow domain dimer (Brasher,2000).