Zebrafish (Danio rerio) Polycomb

Chromobox Homolog 2 (Pc1, cbx2); 4 (Pc2, cbx4); 8 (Pc3, cbx8)

Reference Sequences (RefSeq)

Permission to use zebrafish image given by Pat Edwards:http://zfish.uoregon.edu/

Zebrafish (Danio rerio) Polycomb

Danio rerio Polycomb  mRNA partial cds (ACCESSION AY029300)

Danio rerio Polycomb 2 (ZPc2) (cbx4) mRNA complete cds (ACCESSION AY186581; AAO32051)

Danio rerio Polycomb 3 (ZPc3) (cbx8) mRNA complete cds (ACCESSION AY179330; AAN87353)

[ CBX8:   Blink;   Blast2;  Song et.al. 2004;  Full Text (PDF) Barry archive ]

Reference Sequence (RefSeq for ZPc2/cbx4):

Danio rerio chromobox homolog 4 (Pc2; Pc class homolog, Drosophila)
            (cbx4), mRNA. (ACCESSION NM_205749) (NP_991312)

Danio rerio Polycomb 1 (Pc1) (cbx2) (ACCESSION AB074154) [Kawamura et.al. 2002; pdf]

Conserved Domain Database (CDD, Cn3D) (To display structure, download Cn3D)

http://snhs-plin.barry.edu/Research/Zebrafish_Polycomb.htm

DEVELOPMENTAL BIOLOGY:
Combing Over the Polycomb Group Proteins
Jean Marx
Science 29 April 2005: 624-626. [Summary] [Full Text] [PDF] {a,b} 

Mary Ann Liebert, Inc., publishers

[Chromobox homolog (cbx): 1, 2, 3, 4, 5, 6, 7, 8]

'Polycomb' (Pc) and other members of the Drosophila Polycomb group gene family are part of a cellular memory system that is responsible for the inheritance of gene activity by progeny cells. Pc shares a homologous domain known as the chromodomain with the Drosophila heterochromatin-binding protein, HP1. To isolate human Pc homologs, Satijn et al. (1997) [pdf] screened a fetal brain cDNA library with a probe containing the nonchromodomain portion of a Xenopus Pc homolog (XPc). They recovered a cDNA encoding a predicted 558-amino acid protein that they designated human Pc2. Human Pc2 and XPc share 48% protein sequence identity. Northern blot analysis revealed that human Pc2 is expressed as a 2.8-kb transcript in all tissues tested with almost equal abundance. Using immunofluorescence, Satijn et al. (1997) found that human Pc2 colocalizes with another human Pc homolog, CBX2 (602770), in interphase nuclei, suggesting that the proteins are part of a complex.

GENE FUNCTION

Based on the results of studies with mutant proteins and overexpression of wildtype protein, Satijn et al. (1997) suggested that human Pc2 is a repressor of protooncogene activity and that interference with human Pc2 function can lead to derepression of protooncogene transcription and subsequently to cellular transformation.

Pc2 recruits the transcriptional corepressor CTBP (602618) to Polycomb group (PcG) bodies. Kagey et al. (2003) [pdf] showed that CTBP is sumoylated at a single lysine. In vitro, CTBP sumoylation minimally required the SUMO E1 and E2 (UBC9; 601661) and SUMO1 (601912). However, Pc2 dramatically enhanced CTBP sumoylation. The authors proposed that, in vivo, this is likely due to the ability of Pc2 to recruit both TBPC and UBC9 to PcG bodies, thereby bringing together substrate and E2 and stimulating the transfer of SUMO to CTBP. These results demonstrated that Pc2 is a SUMO E3 and suggested that PcG bodies may be sumoylation centers.

LOCUS       NM_205749               1942 bp    mRNA    linear   VRT 28-OCT-2004
DEFINITION  Danio rerio chromobox homolog 4 (Pc class homolog, Drosophila)
            (cbx4), mRNA.
ACCESSION   NM_205749
VERSION     NM_205749.1  GI:45387904
KEYWORDS    .
SOURCE      Danio rerio (zebrafish)
  ORGANISM  Danio rerio

REFERENCE   1  (bases 1 to 1942)
  AUTHORS   Lin,Y.-W.P., Petrino,T.R. and Packert,G.R.
  TITLE     Danio rerio (zebrafish) Polycomb 2 (ZPc2) mRNA

Submitted (22-NOV-2002) School of Natural and Health Sciences,
            Barry University, 11300 NE Second Avenue, Miami Shores, FL
            33161-6695, USA

COMMENT     PROVISIONAL REFSEQ: This record has not yet been subject to final
            NCBI review. The reference sequence was derived from AY186581.1.

OTHER  cbx4  GENE / MARKER PAGES: LocusLink:403073 (1) (2)

[Chromobox homolog (cbx):  2 (Pc1),  4 (Pc2),  8 (Pc3)]

General protein information Names:   chromobox homolog 4 (Pc class homolog, Drosophila), cbx4     polycomb 2    NCBI Reference Sequences (RefSeq) mRNA Sequence NM_205749 Source Sequence AY186581 Product NP_991312 chromobox homolog 4 (Pc class homolog, Drosophila) Conserved Domains (1) summary cd00024: CHROMO; Chromatin organization modifier (chromo) domain is a conserved region of around 50 amino acids found in a variety of chromosomal proteins, which appear to play a role in the functional organization of the eukaryotic nucleus Location:   10   -   60   Blast   Score:   136

HomoloGene is a system for automated detection of homologs among the annotated genes of several completely sequenced eukaryotic genomes.

HomoloGene:2712. Gene conserved in Mammalia (Pc2, cbx4)

Conserved Domains
Conserved Domains from CDD found in protein sequences by rpsblast searching

cd00024
  CHROMO. Chromatin organization modifier (chromo) domain is a conserved region of around 50 amino acids found in a variety of chromosomal proteins, which appear to play a role in the functional organization of the eukaryotic nucleus
 

UniGene
Links to groups of transcribed sequences established by tblastn searching of UniGene

	A.thaliana  At.7322 Like heterochromatin protein (LHP1)
	D.rerio  Dr.20970 Chromobox homolog 4 (Pc class homolog, Drosophila)

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Gene Name:  chromobox homolog 4 (Pc class homolog, Drosophila)
Gene Symbol: cbx4
Previous Names:
Nomenclature History
/db_xref="ZFIN:ZDB-GENE-040329-2; SWISS-PROT:Q804D1 (1)

	HUGO Gene  Nomenclature Committee
Approved Gene Symbol	Approved Gene Name	Location	Sequence Accession IDs	Previous Symbols	Aliases
CBX4	chromobox homolog 4 (Pc class homolog, Drosophila)	17q25.3	AF013956 Satijn et.al. 1997		hPC2, PC2

Zebrafish Earns Its Stripes in Genetic Screens (Vogel 2000)

Blast  Link  (BLink)

BLink ("BLAST Link") displays the results of BLAST searches that have been done for every protein sequence in the Entrez Proteins data domain.

Blink using the Zebrafish Polycomb 2 (cbx4) as Query  (BLink Result )

Query: gi|28207626 polycomb 2 [Danio rerio]
Matching gi: 45387905

Blink using the Zebrafish Polycomb 3 (cbx8) as Query  ( BLink Result )

Query: gi|27374197 polycomb 3 [Danio rerio]