Chromobox protein homolog 3

Chromobox protein homolog 3 (CBX3) is a 183-amino acid heterochromatin component that recognizes and binds histone H3 tails methylated at lysine-9, directing epigenetic repression (UniProt: Q13185). It also engages histone H1.4 methylated at lysine-26 and participates in kinetochore assembly through interaction with MIS12 complex proteins. CBX3 contributes to chromatin remodeling by recruiting methyltransferases SUV39H1 and SUV39H2 to circadian gene regulatory regions and facilitates NIPBL recruitment to DNA double-strand break sites (UniProt: Q13185).

CBX3 operates within heterochromatin-mediated epigenetic regulation and DNA damage response pathways. No Mendelian disease associations are documented in UniProt for this protein.

CBX3 shows increased abundance in Alzheimer's Disease brain tissue. Chaparral AD proteomics analysis of post-mortem AD brain versus age-matched controls using quantitative mass spectrometry detected CBX3 upregulation with a mean log2 fold-change of +0.472 across one subcellular fraction (Chaparral AD proteomics). This elevation may reflect altered chromatin dynamics or epigenetic remodeling processes relevant to AD neuropathology.