CBX5/HP1 alpha is a component of heterochromatin. It recognizes and binds to histone H3 tails methylated at ‘Lys-9’, leading to epigenetic repression of transcription. HP1 alpha may also interact with lamin B receptor (LBR), thereby contributing to the association of the heterochromatin with the inner nuclear membrane. Further, HP1 alpha is involved in the formation of a functional kinetochore through interaction with MIS12 complex proteins.