NCIt synonyms : Epididymis Luminal Protein 25; Antigen p25; HP1 Alpha; CBX5; Heterochromatin Protein 1 Homolog Alpha; Heterochromatin Protein 1-Alpha;
NCIt 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.;
NCIt note : The human homolog of Drosophila Su(var) 205. This protein binds histone H3 tails methylated
at 'Lys-9' (H3K9me), which is associated with epigenetic repression.;