CBX4

CBX4 (Chromobox 4) is a Protein Coding gene. Among its related pathways are SUMOylation and Metabolism of proteins. Gene Ontology (GO) annotations related to this gene include chromatin binding and ligase activity. An important paralog of this gene is CBX2.

Full Name

Chromobox 4

Function

E3 SUMO-protein ligase which facilitates SUMO1 conjugation by UBE2I (PubMed:12679040).
Involved in the sumoylation of HNRNPK, a p53/TP53 transcriptional coactivator, hence indirectly regulates p53/TP53 transcriptional activation resulting in p21/CDKN1A expression. Monosumoylates ZNF131 (PubMed:22825850).
Component of a Polycomb group (PcG) multiprotein PRC1-like complex, a complex class required to maintain the transcriptionally repressive state of many genes, including Hox genes, throughout development (PubMed:12167701, PubMed:19636380, PubMed:21282530).
PcG PRC1 complex acts via chromatin remodeling and modification of histones; it mediates monoubiquitination of histone H2A 'Lys-119', rendering chromatin heritably changed in its expressibility (PubMed:12167701, PubMed:19636380, PubMed:21282530).
Binds to histone H3 trimethylated at 'Lys-9' (H3K9me3) (By similarity).
Plays a role in the lineage differentiation of the germ layers in embryonic development (By similarity).

Biological Process

Chromatin organization Source: UniProtKB-KW
Negative regulation of apoptotic process Source: ProtInc
Negative regulation of transcription, DNA-templated Source: UniProtKB
Negative regulation of transcription by RNA polymerase II Source: UniProtKB

Cellular Location

Nucleus; Nucleus speckle. Localization to nuclear polycomb bodies is required for ZNF131 sumoylation (PubMed:22467880). Localized in distinct foci on chromatin (PubMed:18927235).

PTM

Phosphorylated on Thr-497 by HIPK2 upon DNA damage. This phosphorylation stimulates E3 SUMO-protein ligase activity and promotes sumoylation on Lys-494, as well as sumoylation of other target proteins, such as HNRNPK.