Chromobox Protein Homolog 5

**Semantic type:** Amino Acid, Peptide, or Protein

**Definition:** Chromobox protein homolog 5 (191 aa, ~22 kDa) is encoded by the human CBX5 gene. This soluble, nuclear protein plays a role in epigenetic modification of chromatin, by catalyzing the monomethylation of lysine 5 of histone H2B. The outcome of this modification is associated with either activated gene transcription, or, if further processed to trimethylated lysine 5, epigenetically repressed gene transcription. By affecting the balance of chromatin in heterochromatin and euchromatin at specific gene loci, this protein acts as a candidate tumor suppressor.

**Synonyms:** - Antigen p25 - CBX5 - Epididymis Luminal Protein 25 - HP1 Alpha - HP1 alpha - Heterochromatin Protein 1 Homolog Alpha - Heterochromatin Protein 1-Alpha