ID:CBX4_HUMAN DESCRIPTION: RecName: Full=E3 SUMO-protein ligase CBX4; EC=6.3.2.-; AltName: Full=Chromobox protein homolog 4; AltName: Full=Polycomb 2 homolog; Short=Pc2; Short=hPc2; FUNCTION: E3 SUMO-protein ligase which facilitates SUMO1 conjugation by UBE2I. Involved in the sumoylation of HNRNPK, a p53/TP53 transcriptional coactivator, hence indirectly regulates p53/TP53 transcriptional activation resulting in p21/CDKN1A expression. FUNCTION: 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. 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. PATHWAY: Protein modification; protein sumoylation. SUBUNIT: Interacts with histone H3-K9Me3 (By similarity). Component of a PRC1-like complex. Self-associates. Interacts with SUV39H1 and HIPK2. Interacts with CSNK2B. INTERACTION: P35226:BMI1; NbExp=2; IntAct=EBI-4392727, EBI-2341576; P68400:CSNK2A1; NbExp=2; IntAct=EBI-4392727, EBI-347804; P67870:CSNK2B; NbExp=2; IntAct=EBI-4392727, EBI-348169; Q9BYE7:PCGF6; NbExp=2; IntAct=EBI-4392727, EBI-1048026; Q99496:RNF2; NbExp=2; IntAct=EBI-4392727, EBI-722416; P31946:YWHAB; NbExp=2; IntAct=EBI-722425, EBI-359815; P62258:YWHAE; NbExp=2; IntAct=EBI-4392727, EBI-356498; P63104:YWHAZ; NbExp=2; IntAct=EBI-4392727, EBI-347088; SUBCELLULAR LOCATION: Nucleus. Nucleus speckle. TISSUE SPECIFICITY: Ubiquitous. DOMAIN: The polyhistidine repeat may act as a targeting signal to nuclear speckles (PubMed:19266028). 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. MISCELLANEOUS: The human orthologuous proteins of Drosphila Polycomb group protein Pc, CBX2, CBX4, CBX6, CBX7 and CBX8, show distinct nulear localizations, contribute differently to transcriptional repression, and appear to be part of distinct PRC1-like protein complexes. The hPRC-H complex purification reported by PubMed:12167701 probably presents a mixture of different complexes. SIMILARITY: Contains 1 chromo domain. SEQUENCE CAUTION: Sequence=AAH14967.1; Type=Miscellaneous discrepancy; Note=Aberrant splicing;
The RNAfold program from the Vienna RNA Package is used to perform the secondary structure predictions and folding calculations. The estimated folding energy is in kcal/mol. The more negative the energy, the more secondary structure the RNA is likely to have.
ModBase Predicted Comparative 3D Structure on O00257
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Orthologous Genes in Other Species
Orthologies between human, mouse, and rat are computed by taking the best BLASTP hit, and filtering out non-syntenic hits. For more distant species reciprocal-best BLASTP hits are used. Note that the absence of an ortholog in the table below may reflect incomplete annotations in the other species rather than a true absence of the orthologous gene.
Biological Process: GO:0000122 negative regulation of transcription from RNA polymerase II promoter GO:0006325 chromatin organization GO:0006351 transcription, DNA-templated GO:0006355 regulation of transcription, DNA-templated GO:0016925 protein sumoylation GO:0043066 negative regulation of apoptotic process GO:0045892 negative regulation of transcription, DNA-templated
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Sequence and Links to Tools and Databases 
Common Gene Haplotype Alleles 
