ph-d

Summary

Gene Symbol: ph-d
Description: polyhomeotic distal
Alias: CG3895, DROZFP, Dmel\CG3895, EG:BACN25G24.3, PH-d, PHD, Ph-d, PhD, ph-D, ph[D], ph[d], phd, phm, polyhomeotic distal, CG3895-PA, CG3895-PB, ph-d-PA, ph-d-PB, polyhomeotic, polyhomeotic proximal, polyhomeotic-distal
Species: fruit fly
Products:     ph-d

Top Publications

  1. Smouse D, Goodman C, Mahowald A, Perrimon N. polyhomeotic: a gene required for the embryonic development of axon pathways in the central nervous system of Drosophila. Genes Dev. 1988;2:830-42 pubmed
    Hypomorphic alleles of the locus polyhomeotic (ph) produce multiple, homeotic-like transformations in adult flies that mimic dominant mutations in the Antennapedia and Bithorax complexes...
  2. Simon J, Chiang A, Bender W, Shimell M, O Connor M. Elements of the Drosophila bithorax complex that mediate repression by Polycomb group products. Dev Biol. 1993;158:131-44 pubmed
    ..constructs are each regulated by the genes Polycomb (Pc), extra sex combs (esc), Enhancer of zeste (E[z]), polyhomeotic (ph), Polycomb-like (Pcl), Sex comb on midleg (Scm), Posterior sex combs (Psc), and Additional sex combs (Asx), ..
  3. Mihaly J, Mishra R, Karch F. A conserved sequence motif in Polycomb-response elements. Mol Cell. 1998;1:1065-6 pubmed
  4. Shao Z, Raible F, Mollaaghababa R, Guyon J, Wu C, Bender W, et al. Stabilization of chromatin structure by PRC1, a Polycomb complex. Cell. 1999;98:37-46 pubmed
    ..Polycomb repressive complex 1), that contains the products of the PcG genes Polycomb, Posterior sex combs, polyhomeotic, Sex combs on midleg, and several other proteins...
  5. O Connell S, Wang L, Robert S, Jones C, Saint R, Jones R. Polycomblike PHD fingers mediate conserved interaction with enhancer of zeste protein. J Biol Chem. 2001;276:43065-73 pubmed
    ..PCL.E(Z) interaction is shown to be mediated by the plant homeodomain (PHD) fingers domain of PCL, providing evidence that this motif can act as an independent protein interaction domain...
  6. Franke A, DeCamillis M, Zink D, Cheng N, Brock H, Paro R. Polycomb and polyhomeotic are constituents of a multimeric protein complex in chromatin of Drosophila melanogaster. EMBO J. 1992;11:2941-50 pubmed
    ..Using immunoprecipitation we show that two members of the Pc-G, Polycomb and polyhomeotic, are constituents of a soluble multimeric protein complex...
  7. DeCamillis M, Cheng N, Pierre D, Brock H. The polyhomeotic gene of Drosophila encodes a chromatin protein that shares polytene chromosome-binding sites with Polycomb. Genes Dev. 1992;6:223-32 pubmed
    ..The polyhomeotic (ph) gene is a member of the PcG of genes...
  8. Kodjabachian L, Delaage M, Maurel C, Miassod R, Jacq B, Rosset R. Mutations in ccf, a novel Drosophila gene encoding a chromosomal factor, affect progression through mitosis and interact with Pc-G mutations. EMBO J. 1998;17:1063-75 pubmed
    ..We also find that mutations in the Pc-G genes Polycomb, polyhomeotic and Enhancer of zeste are enhanced by ccf mutations...
  9. Moehrle A, Paro R. Spreading the silence: epigenetic transcriptional regulation during Drosophila development. Dev Genet. 1994;15:478-84 pubmed
    ..Analysis of these functions in Drosophila provides an excellent model system for studying the molecular basis of such epigenetic mechanisms that use higher order chromatin structures for transcriptional repression. ..

More Information

Publications68

  1. Maeda R, Karch F. The ABC of the BX-C: the bithorax complex explained. Development. 2006;133:1413-22 pubmed
    ..This primer attempts to distill and explain our current knowledge about this classic, complex locus. ..
  2. Martinez A, Colomb S, Déjardin J, Bantignies F, Cavalli G. Polycomb group-dependent Cyclin A repression in Drosophila. Genes Dev. 2006;20:501-13 pubmed
    ..This sequence is bound by the Polycomb (PC) and Polyhomeotic (PH) proteins of the PcG, and also by GAGA factor (GAF), a trxG protein that is usually found associated with ..
  3. Mills A. Throwing the cancer switch: reciprocal roles of polycomb and trithorax proteins. Nat Rev Cancer. 2010;10:669-82 pubmed publisher
    ..Recent work highlights the dynamic interplay between these opposing classes of proteins, providing new avenues for understanding how these epigenetic regulators function in tumorigenesis. ..
  4. Beuchle D, Struhl G, Muller J. Polycomb group proteins and heritable silencing of Drosophila Hox genes. Development. 2001;128:993-1004 pubmed
    ..Some PcG proteins may be required to define and propagate this mark; others may function to repress the transcription of Hox genes that bear the mark. ..
  5. Nekrasov M, Klymenko T, Fraterman S, Papp B, Oktaba K, Kocher T, et al. Pcl-PRC2 is needed to generate high levels of H3-K27 trimethylation at Polycomb target genes. EMBO J. 2007;26:4078-88 pubmed
    ..Pcl-PRC2 is thus the HMTase that generates the high levels of H3-K27 trimethylation in Polycomb target genes that are needed to maintain a Polycomb-repressed chromatin state. ..
  6. Mulholland N, King I, Kingston R. Regulation of Polycomb group complexes by the sequence-specific DNA binding proteins Zeste and GAGA. Genes Dev. 2003;17:2741-6 pubmed
    ..GAGA does not stably associate with PCC, but nucleosomal templates bound by GAGA are more efficiently bound and more efficiently inhibited by PCC. Thus Zeste and GAGA factor use distinct means to increase repression mediated by PRC1. ..
  7. Rastelli L, Chan C, Pirrotta V. Related chromosome binding sites for zeste, suppressors of zeste and Polycomb group proteins in Drosophila and their dependence on Enhancer of zeste function. EMBO J. 1993;12:1513-22 pubmed
    ..two proteins were compared with those of zeste protein and two other Polycomb group proteins, Polycomb and polyhomeotic. The five proteins co-localize at a large number of sites, suggesting that they frequently act together on ..
  8. Mohd Sarip A, Lagarou A, Doyen C, van der Knaap J, Aslan U, Bezstarosti K, et al. Transcription-independent function of Polycomb group protein PSC in cell cycle control. Science. 2012;336:744-7 pubmed publisher
    ..Thus, PSC appears to mediate both developmental gene silencing and posttranslational control of mitosis. Direct regulation of cell cycle progression might be a crucial part of the PcG system's function in development and cancer. ..
  9. Paro R. Mechanisms of heritable gene repression during development of Drosophila. Curr Opin Cell Biol. 1993;5:999-1005 pubmed
    ..Recent experiments demonstrate that, in particular, the heritable inactivation of regulatory genes relies on stable changes in the higher-order constitution of chromatin. ..
  10. Simon J. Locking in stable states of gene expression: transcriptional control during Drosophila development. Curr Opin Cell Biol. 1995;7:376-85 pubmed
  11. Breiling A, O Neill L, D Eliseo D, Turner B, Orlando V. Epigenome changes in active and inactive polycomb-group-controlled regions. EMBO Rep. 2004;5:976-82 pubmed
    ..These PcG-specific repressive marks are maintained by the action of the E(z) HMT, an enzyme that has an important role not only in establishing but also in maintaining PcG repression. ..
  12. Brown J, Fritsch C, Mueller J, Kassis J. The Drosophila pho-like gene encodes a YY1-related DNA binding protein that is redundant with pleiohomeotic in homeotic gene silencing. Development. 2003;130:285-94 pubmed
    ..In contrast to Pho and Pho-like, removal of Trithorax-like/GAGA factor or Zeste, two other DNA-binding proteins implicated in PRE function, does not cause misexpression of homeotic genes or reporter genes in imaginal disks. ..
  13. Martin E, Adler P. The Polycomb group gene Posterior Sex Combs encodes a chromosomal protein. Development. 1993;117:641-55 pubmed
    ..In all cases, it is nuclear, as is its mammalian homolog, the bmi-1 protein. On polytene chromosomes, we find Psc at 45 chromosomal loci where two other Pc-G proteins are present. ..
  14. Schaaf C, Misulovin Z, Gause M, Koenig A, Gohara D, Watson A, et al. Cohesin and polycomb proteins functionally interact to control transcription at silenced and active genes. PLoS Genet. 2013;9:e1003560 pubmed publisher
    ..These studies reveal a previously unrecognized role for PRC1 in facilitating productive gene transcription and provide new insights into how cohesin and PRC1 control development. ..
  15. Moazed D, O Farrell P. Maintenance of the engrailed expression pattern by Polycomb group genes in Drosophila. Development. 1992;116:805-10 pubmed
  16. O Dor E, Beck S, Brock H. Polycomb group mutants exhibit mitotic defects in syncytial cell cycles of Drosophila embryos. Dev Biol. 2006;290:312-22 pubmed
    ..Previously, two PcG mutants, polyhomeotic and Enhancer of zeste, were shown to exhibit mitotic segregation defects in embryos, and condensation defects ..
  17. Bienz M. Molecular mechanisms of determination in Drosophila. Curr Opin Cell Biol. 1992;4:955-61 pubmed
    ..Interactions between these proteins and their target selector genes are beginning to be understood, shaping our molecular view as to how stable determination of cells is achieved. ..
  18. Feng S, Huang J, Wang J. Loss of the Polycomb group gene polyhomeotic induces non-autonomous cell overproliferation. EMBO Rep. 2011;12:157-63 pubmed publisher
    ..Here, we report that mutant clones of the PcG gene polyhomeotic (ph) form unique single-cell-layer cavities that secrete three JAK/STAT pathway ligands, which in turn act ..
  19. Paro R. Imprinting a determined state into the chromatin of Drosophila. Trends Genet. 1990;6:416-21 pubmed
  20. Pirrotta V, Rastelli L. White gene expression, repressive chromatin domains and homeotic gene regulation in Drosophila. Bioessays. 1994;16:549-56 pubmed
    ..Such complexes, which normally regulate the expression of many genes, including the homeotic loci, are responsible for silencing, white gene variegation, pairing-dependent effects and insertional targeting. ..
  21. Salvaing J, Decoville M, Mouchel Vielh E, Bussiere M, Daulny A, Boldyreva L, et al. Corto and DSP1 interact and bind to a maintenance element of the Scr Hox gene: understanding the role of Enhancers of trithorax and Polycomb. BMC Biol. 2006;4:9 pubmed
    ..The presence of a given combination of ETPs on an ME would control the recruitment of either PcG or TrxG complexes, propagating the silenced or active state. ..
  22. Dura J, Ingham P. Tissue- and stage-specific control of homeotic and segmentation gene expression in Drosophila embryos by the polyhomeotic gene. Development. 1988;103:733-41 pubmed
    ..and of the segmentation genes, fushi tarazu (ftz), even skipped (eve) and engrailed (en) have been monitored in polyhomeotic (ph) mutant embryos...
  23. Déjardin J, Cavalli G. Chromatin inheritance upon Zeste-mediated Brahma recruitment at a minimal cellular memory module. EMBO J. 2004;23:857-68 pubmed
    ..Thus, epigenetic inheritance of active chromatin states involves the recruitment of multiple cooperative chromatin-modifying complexes at closely spaced but distinct sites within a CMM. ..
  24. Lagarou A, Mohd Sarip A, Moshkin Y, Chalkley G, Bezstarosti K, Demmers J, et al. dKDM2 couples histone H2A ubiquitylation to histone H3 demethylation during Polycomb group silencing. Genes Dev. 2008;22:2799-810 pubmed publisher
    ..Thus, dRAF removes an active mark from histone H3 and adds a repressive one to H2A. These findings reveal coordinate trans-histone regulation by a PcG complex to mediate gene repression. ..
  25. Martinez A, Schuettengruber B, Sakr S, Janic A, Gonzalez C, Cavalli G. Polyhomeotic has a tumor suppressor activity mediated by repression of Notch signaling. Nat Genet. 2009;41:1076-82 pubmed publisher
    ..eye as a model system, we show that cells with mutations in the gene locus (ph) that encodes the PcG protein Polyhomeotic (PH) overproliferate and lose both the ability to differentiate and their normal polarity...
  26. DeVido S, Kwon D, Brown J, Kassis J. The role of Polycomb-group response elements in regulation of engrailed transcription in Drosophila. Development. 2008;135:669-76 pubmed publisher
    ..Our data are consistent with the model that engrailed PREs bring chromatin together, allowing both positive and negative regulatory interactions between distantly located DNA fragments. ..
  27. Buchenau P, Hodgson J, Strutt H, Arndt Jovin D. The distribution of polycomb-group proteins during cell division and development in Drosophila embryos: impact on models for silencing. J Cell Biol. 1998;141:469-81 pubmed
    The subcellular three-dimensional distribution of three polycomb-group (PcG) proteins-polycomb, polyhomeotic and posterior sex combs-in fixed whole-mount Drosophila embryos was analyzed by multicolor confocal fluorescence microscopy...
  28. Gutierrez L, Oktaba K, Scheuermann J, Gambetta M, Ly Hartig N, Muller J. The role of the histone H2A ubiquitinase Sce in Polycomb repression. Development. 2012;139:117-27 pubmed publisher
    ..Class II genes are only misexpressed in animals lacking the Psc-Su(z)2 and Polyhomeotic (Ph) subunits but remain stably repressed in the absence of the Sce and Polycomb (Pc) subunits...
  29. Enderle D, Beisel C, Stadler M, Gerstung M, Athri P, Paro R. Polycomb preferentially targets stalled promoters of coding and noncoding transcripts. Genome Res. 2011;21:216-26 pubmed publisher
    ..Interestingly, this set includes previously unknown promoters for primary transcripts of microRNA genes, thereby expanding the scope of Polycomb control to noncoding RNAs essential for development, apoptosis, and growth. ..
  30. Campbell R, Sinclair D, Couling M, Brock H. Genetic interactions and dosage effects of Polycomb group genes of Drosophila. Mol Gen Genet. 1995;246:291-300 pubmed
    ..Flies with increasing doses of esc+ exhibit anterior transformations, but these are not enhanced by mutations in trithorax group genes. The results are discussed with respect to current models of Pc group function. ..
  31. Beisswanger S, Stephan W. Evidence that strong positive selection drives neofunctionalization in the tandemly duplicated polyhomeotic genes in Drosophila. Proc Natl Acad Sci U S A. 2008;105:5447-52 pubmed publisher
    The polyhomeotic (ph) locus in Drosophila melanogaster consists of the two tandemly duplicated genes ph-d (distal) and ph-p (proximal)...
  32. Papp B, Muller J. Histone trimethylation and the maintenance of transcriptional ON and OFF states by trxG and PcG proteins. Genes Dev. 2006;20:2041-54 pubmed
  33. Grimaud C, Bantignies F, Pal Bhadra M, Ghana P, Bhadra U, Cavalli G. RNAi components are required for nuclear clustering of Polycomb group response elements. Cell. 2006;124:957-71 pubmed
    ..This suggests a novel role for the RNAi machinery in regulating the nuclear organization of PcG chromatin targets. ..
  34. Peterson A, Mallin D, Francis N, Ketel C, Stamm J, Voeller R, et al. Requirement for sex comb on midleg protein interactions in Drosophila polycomb group repression. Genetics. 2004;167:1225-39 pubmed
    ..This domain is found in SCM and in another PcG protein, Polyhomeotic (PH), which is a core component of Polycomb repressive complex 1 (PRC1)...
  35. Salvaing J, Lopez A, Boivin A, Deutsch J, Peronnet F. The Drosophila Corto protein interacts with Polycomb-group proteins and the GAGA factor. Nucleic Acids Res. 2003;31:2873-82 pubmed
    ..These results reinforce the idea that Corto plays a role in PcG silencing, perhaps by confering target specificity. ..
  36. King I, Francis N, Kingston R. Native and recombinant polycomb group complexes establish a selective block to template accessibility to repress transcription in vitro. Mol Cell Biol. 2002;22:7919-28 pubmed
    ..These results suggest that PcG proteins do not merely prohibit all transcription machinery from binding the template but instead likely inhibit specific steps in the transcription reaction. ..
  37. Serrano N, Brock H, Demeret C, Dura J, Randsholt N, Kornberg T, et al. polyhomeotic appears to be a target of engrailed regulation in Drosophila. Development. 1995;121:1691-703 pubmed
    ..One of its regulatory targets appears to be polyhomeotic (ph), a Polycomb group gene...
  38. Ficz G, Heintzmann R, Arndt Jovin D. Polycomb group protein complexes exchange rapidly in living Drosophila. Development. 2005;132:3963-76 pubmed
  39. Classen A, Bunker B, Harvey K, Vaccari T, Bilder D. A tumor suppressor activity of Drosophila Polycomb genes mediated by JAK-STAT signaling. Nat Genet. 2009;41:1150-5 pubmed publisher
    ..These findings show that PcG proteins can restrict growth directly by silencing mitogenic signaling pathways, shedding light on an epigenetic mechanism underlying tumor suppression. ..
  40. Lonie A, D ANDREA R, Paro R, Saint R. Molecular characterisation of the Polycomblike gene of Drosophila melanogaster, a trans-acting negative regulator of homeotic gene expression. Development. 1994;120:2629-36 pubmed
    ..larval salivary gland polytene chromosomes at about 100 specific loci, the same loci to which the Polycomb and polyhomeotic proteins, two other Polycomb Group proteins, are found...
  41. Schwartz Y, Kahn T, Nix D, Li X, Bourgon R, Biggin M, et al. Genome-wide analysis of Polycomb targets in Drosophila melanogaster. Nat Genet. 2006;38:700-5 pubmed
    ..PcG targets are highly enriched in genes encoding transcription factors, but they also include genes coding for receptors, signaling proteins, morphogens and regulators representing all major developmental pathways. ..
  42. Kim C, Sawaya M, Cascio D, Kim W, Bowie J. Structural organization of a Sex-comb-on-midleg/polyhomeotic copolymer. J Biol Chem. 2005;280:27769-75 pubmed
    ..Here we examine the interaction between the SAM domains of the polycomb group proteins polyhomeotic (Ph) and Sex-comb-on-midleg (Scm). Previously we showed that Ph-SAM polymerizes as a helical structure...
  43. Dura J, Randsholt N, Deatrick J, Erk I, Santamaria P, Freeman J, et al. A complex genetic locus, polyhomeotic, is required for segmental specification and epidermal development in D. melanogaster. Cell. 1987;51:829-39 pubmed
    Two mutagenic events are required to make null mutations of polyhomeotic (ph), which suggests that the locus is complex...
  44. Narbonne K, Besse F, Brissard Zahraoui J, Pret A, Busson D. polyhomeotic is required for somatic cell proliferation and differentiation during ovarian follicle formation in Drosophila. Development. 2004;131:1389-400 pubmed
    The polyhomeotic (ph) gene of Drosophila is a member of the Polycomb group (Pc-G) genes, which are required for maintenance of a repressed state of homeotic gene transcription, which stabilizes cell identity throughout development...
  45. Chen X, Hiller M, Sancak Y, Fuller M. Tissue-specific TAFs counteract Polycomb to turn on terminal differentiation. Science. 2005;310:869-72 pubmed
    ..Testis TAFs also promoted relocalization of Polycomb Repression Complex 1 components to the nucleolus in spermatocytes, implicating subnuclear architecture in the regulation of terminal differentiation. ..
  46. Chanas G, Lavrov S, Iral F, Cavalli G, Maschat F. Engrailed and polyhomeotic maintain posterior cell identity through cubitus-interruptus regulation. Dev Biol. 2004;272:522-35 pubmed
    ..We show here that engrailed and polyhomeotic (ph), a member of the Polycomb Group (PcG) genes, act concomitantly to maintain the repression of ci in ..
  47. Orlando V, Paro R. Chromatin multiprotein complexes involved in the maintenance of transcription patterns. Curr Opin Genet Dev. 1995;5:174-9 pubmed
    ..The role of the trithorax-group factors is to counteract these repressed chromatin domains and thus to render the genes accessible to activating factors. ..
  48. Schuettengruber B, Ganapathi M, Leblanc B, Portoso M, Jaschek R, Tolhuis B, et al. Functional anatomy of polycomb and trithorax chromatin landscapes in Drosophila embryos. PLoS Biol. 2009;7:e13 pubmed publisher
    ..Furthermore, several DNA sequence features discriminate between PcG- and TRX-N-bound regions, indicating that underlying DNA sequence contains critical information to drive PREs and TREs towards silencing or activation. ..
  49. Klymenko T, Papp B, Fischle W, Kocher T, Schelder M, Fritsch C, et al. A Polycomb group protein complex with sequence-specific DNA-binding and selective methyl-lysine-binding activities. Genes Dev. 2006;20:1110-22 pubmed
    ..We propose that PRE-tethered PhoRC selectively interacts with methylated histones in the chromatin flanking PREs to maintain a Polycomb-repressed chromatin state. ..
  50. Oktaba K, Gutierrez L, Gagneur J, Girardot C, Sengupta A, Furlong E, et al. Dynamic regulation by polycomb group protein complexes controls pattern formation and the cell cycle in Drosophila. Dev Cell. 2008;15:877-89 pubmed publisher
    ..Analysis of cell cycle regulators indicates that the PcG system also dynamically modulates the expression levels of certain genes, providing a possible explanation for the tumor phenotype of PcG mutants. ..
  51. Gorfinkiel N, Fanti L, Melgar T, García E, Pimpinelli S, Guerrero I, et al. The Drosophila Polycomb group gene Sex combs extra encodes the ortholog of mammalian Ring1 proteins. Mech Dev. 2004;121:449-62 pubmed
    ..chromosomes, 70% of which overlap those of other PcG products such as Polycomb, Posterior sex combs and Polyhomeotic, and 30% of which are unique...
  52. Strübbe G, Popp C, Schmidt A, Pauli A, Ringrose L, Beisel C, et al. Polycomb purification by in vivo biotinylation tagging reveals cohesin and Trithorax group proteins as interaction partners. Proc Natl Acad Sci U S A. 2011;108:5572-7 pubmed publisher
    ..Furthermore, our analysis revealed an association of PcG protein complexes with the cohesin complex and showed that Polycomb-dependent silencing of a transgenic reporter depends on cohesin function. ..
  53. Simon J, Chiang A, Bender W. Ten different Polycomb group genes are required for spatial control of the abdA and AbdB homeotic products. Development. 1992;114:493-505 pubmed
    ..Embryos containing mutations in the genes Polycomb (Pc), extra sex combs (esc), Enhancer of zeste [E(z)], polyhomeotic (ph), Sex comb on midleg (Scm), Polycomb-like (Pcl), Sex comb extra (Sce), Additional sex combs (Asx), ..
  54. Mohd Sarip A, van der Knaap J, Wyman C, Kanaar R, Schedl P, Verrijzer C. Architecture of a polycomb nucleoprotein complex. Mol Cell. 2006;24:91-100 pubmed
    ..Indeed, chromatin immunoprecipitations (ChIPs) and nuclease mapping demonstrated that PREs are nucleosome depleted in vivo. We discuss the implications of these findings for models explaining PRE function. ..
  55. Breiling A, Turner B, Bianchi M, Orlando V. General transcription factors bind promoters repressed by Polycomb group proteins. Nature. 2001;412:651-5 pubmed
    ..We further show that PcG proteins interact in vitro with GTFs. We suggest that PcG complexes maintain silencing by inhibiting GTF-mediated activation of transcription. ..
  56. Cheng N, Sinclair D, Campbell R, Brock H. Interactions of polyhomeotic with Polycomb group genes of Drosophila melanogaster. Genetics. 1994;138:1151-62 pubmed
    ..Recently, it was shown that polyhomeotic (ph) immunoprecipitates in a multimeric complex that includes Pc...
  57. Pirrotta V. Chromatin complexes regulating gene expression in Drosophila. Curr Opin Genet Dev. 1995;5:466-72 pubmed
    ..How they persist through cell proliferation and how they silence gene activity are still open issues. ..
  58. Tolhuis B, de Wit E, Muijrers I, Teunissen H, Talhout W, van Steensel B, et al. Genome-wide profiling of PRC1 and PRC2 Polycomb chromatin binding in Drosophila melanogaster. Nat Genet. 2006;38:694-9 pubmed
    ..These results highlight the extensive involvement of PcG proteins in the coordination of development through the formation of large repressive chromatin domains. ..
  59. Petruk S, Smith S, Sedkov Y, Mazo A. Association of trxG and PcG proteins with the bxd maintenance element depends on transcriptional activity. Development. 2008;135:2383-90 pubmed publisher
    ..There is, however, no overall synergism or antagonism between and within the trxG and PcG proteins and, instead, only subsets of trxG proteins act synergistically. ..