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Results for “Polycomb Repressive Complex 1”

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PubMed1998

Maternal control of embryogenesis by MEDEA, a polycomb group gene in Arabidopsis.

The gametophytic maternal effect mutant medea (mea) shows aberrant growth regulation during embryogenesis in Arabidopsis thaliana. Embryos derived from mea eggs grow excessively and die during seed desiccation. Embryo lethality is independent of the paternal contribution and gene dosage. The mea phenotype is consistent with the parental conflict theory for the evolution of parent-of-origin-specific effects. MEA encodes a SET domain protein similar to Enhancer of zeste, a member of the Polycomb group. In animals, Polycomb group proteins ensure the stable inheritance of expression patterns through cell division and regulate the control of cell proliferation.

Alleles↗

PubMed2007

The N terminus of Drosophila ESC binds directly to histone H3 and is required for E(Z)-dependent trimethylation of H3 lysine 27.

Polycomb group proteins mediate heritable transcriptional silencing and function through multiprotein complexes that methylate and ubiquitinate histones. The 600-kDa E(Z)/ESC complex, also known as Polycomb repressive complex 2 (PRC2), specifically methylates histone H3 lysine 27 (H3 K27) through the intrinsic histone methyltransferase (HMTase) activity of the E(Z) SET domain. By itself, E(Z) exhibits no detectable HMTase activity and requires ESC for methylation of H3 K27. The molecular basis for this requirement is unknown. ESC binds directly, via its C-terminal WD repeats (beta-propeller domain), to E(Z). Here, we show that the N-terminal region of ESC that precedes its beta-propeller domain interacts directly with histone H3, thereby physically linking E(Z) to its substrate. We show that when expressed in stable S2 cell lines, an N-terminally truncated ESC (FLAG-ESC61-425), like full-length ESC, is incorporated into complexes with E(Z) and binds to a Ubx Polycomb response element in a chromatin immunoprecipitation assay. However, incorporation of this N-terminally truncated ESC into E(Z) complexes prevents trimethylation of histone H3 by E(Z). We also show that a closely related Drosophila melanogaster paralog of ESC, ESC-like (ESCL), and the mammalian homolog of ESC, EED, also interact with histone H3 via their N termini, indicating that the interaction of ESC with histone H3 is evolutionarily conserved, reflecting its functional importance. Our data suggest that one of the roles of ESC (and ESCL and EED) in PRC2 complexes is to enable E(Z) to utilize histone H3 as a substrate by physically linking enzyme and substrate.

Animals↗

PubMed1997

Evolutionary conservation and predicted structure of the Drosophila extra sex combs repressor protein.

The Drosophila extra sex combs (esc) protein, a member of the Polycomb group (PcG), is a transcriptional repressor of homeotic genes. Genetic studies have shown that esc protein is required in early embryos at about the time that other PcG proteins become engaged in homeotic gene repression. The esc protein consists primarily of multiple copies of the WD repeat, a motif that has been implicated in protein-protein interaction. To further investigate the domain organization of esc protein, we have isolated and characterized esc homologs from divergent insect species. We report that esc protein is highly conserved in housefly (72% identical to Drosophila esc), butterfly (55% identical), and grasshopper (56% identical). We show that the butterfly homolog provides esc function in Drosophila, indicating that the sequence similarities reflect functional conservation. Homology modeling using the crystal structure of another WD repeat protein, the G-protein beta-subunit, predicts that esc protein adopts a beta-propeller structure. The sequence comparisons and modeling suggest that there are seven WD repeats in esc protein which together form a seven-bladed beta-propeller. We locate the conserved regions in esc protein with respect to this predicted structure. Site-directed mutagenesis of specific loops, predicted to extend from the propeller surface, identifies conserved parts of esc protein required for function in vivo. We suggest that these regions might mediate physical interaction with esc partner proteins.

Amino Acid Sequence↗

PubMed1997

The product of the murine homolog of the Drosophila extra sex combs gene displays transcriptional repressor activity.

The heterogeneous nuclear ribonucleoprotein K protein represents a novel class of proteins that may act as docking platforms that orchestrate cross-talk among molecules involved in signal transduction and gene expression. Using a fragment of K protein as bait in the yeast two-hybrid screen, we isolated a cDNA that encodes a protein whose primary structure has extensive similarity to the Drosophila melanogaster extra sex combs (esc) gene product, Esc, a putative silencer of homeotic genes. The cDNA that we isolated is identical to the cDNA of the recently positionally cloned mouse embryonic ectoderm development gene, eed. Like Esc, Eed contains six WD-40 repeats in the C-terminal half of the protein and is thought to repress homeotic gene expression during mouse embryogenesis. Eed binds to K protein through a domain in its N terminus, but interestingly, this domain is not found in the Drosophila Esc. Gal4-Eed fusion protein represses transcription of a reporter gene driven by a promoter that contains Gal4-binding DNA elements. Eed also represses transcription when recruited to a target promoter by Gal4-K protein. Point mutations within the eed gene that are responsible for severe embryonic development abnormalities abolished the transcriptional repressor activity of Eed. Results of this study suggest that Eed-restricted homeotic gene expression during embryogenesis reflects the action of Eed as a transcriptional repressor. The Eed-mediated transcriptional effects are likely to reflect the interaction of Eed with multiple molecular partners, including K protein.

Amino Acid Sequence↗

PubMed1998

The Drosophila esc and E(z) proteins are direct partners in polycomb group-mediated repression.

The extra sex combs (esc) and Enhancer of zeste [E(z)] proteins are members of the Drosophila Polycomb group (Pc-G) of transcriptional repressors. Here we present evidence for direct physical interaction between the esc and E(z) proteins using yeast two-hybrid and in vitro binding assays. In addition, coimmunoprecipitation from embryo extracts demonstrates association of esc and E(z) in vivo. We have delimited the esc-binding domain of E(z) to an N-terminal 33-amino-acid region. Furthermore, we demonstrate that site-directed mutations in the esc protein previously shown to impair esc function in vivo disrupt esc-E(z) interactions in vitro. We also show an in vitro interaction between the heed and EZH1 proteins, which are human homologs of esc and E(z), respectively. These results suggest that the esc-E(z) molecular partnership has been conserved in evolution. Previous studies suggested that esc is primarily involved in the early stages of Pc-G-mediated silencing during embryogenesis. However, E(z) is continuously required in order to maintain chromosome binding by other Pc-G proteins. In light of these earlier observations and the molecular data presented here, we discuss how esc-E(z) protein complexes may contribute to transcriptional silencing by the Pc-G.

Amino Acid Sequence↗

PubMed1998

Interaction of mouse polycomb-group (Pc-G) proteins Enx1 and Enx2 with Eed: indication for separate Pc-G complexes.

The Polycomb group (Pc-G) constitutes an important, functionally conserved group of proteins, required to stably maintain inactive homeobox genes repressed during development. Drosophila extra sex combs (esc) and its mammalian homolog embryonic ectoderm development (eed) are special Pc-G members, in that they are required early during development when Pc-G repression is initiated, a process that is still poorly understood. To get insight in the molecular function of Eed, we searched for Eed-interacting proteins, using the yeast two-hybrid method. Here we describe the specific in vivo binding of Eed to Enx1 and Enx2, two mammalian homologs of the essential Drosophila Pc-G gene Enhancer-of-zeste [E(z)]. No direct biochemical interactions were found between Eed/Enx and a previously characterized mouse Pc-G protein complex, containing several mouse Pc-G proteins including mouse polyhomeotic (Mph1). This suggests that different Pc-G complexes with distinct functions may exist. However, partial colocalization of Enx1 and Mph1 to subnuclear domains may point to more transient interactions between these complexes, in support of a bridging role for Enx1.

Animals↗

PubMed2000

A Drosophila ESC-E(Z) protein complex is distinct from other polycomb group complexes and contains covalently modified ESC.

The extra sex combs (ESC) and Enhancer of zeste [E(Z)] proteins, members of the Polycomb group (PcG) of transcriptional repressors, interact directly and are coassociated in fly embryos. We report that these two proteins are components of a 600-kDa complex in embryos. Using gel filtration and affinity chromatography, we show that this complex is biochemically distinct from previously described complexes containing the PcG proteins Polyhomeotic, Polycomb, and Sex comb on midleg. In addition, we present evidence that ESC is phosphorylated in vivo and that this modified ESC is preferentially associated in the complex with E(Z). Modified ESC accumulates between 2 and 6 h of embryogenesis, which is the developmental time when esc function is first required. We find that mutations in E(z) reduce the ratio of modified to unmodified ESC in vivo. We have also generated germ line transformants that express ESC proteins bearing site-directed mutations that disrupt ESC-E(Z) binding in vitro. These mutant ESC proteins fail to provide esc function, show reduced levels of modification in vivo, and are still assembled into complexes. Taken together, these results suggest that ESC phosphorylation normally occurs after assembly into ESC-E(Z) complexes and that it contributes to the function or regulation of these complexes. We discuss how biochemically separable ESC-E(Z) and PC-PH complexes might work together to provide PcG repression.

Animals↗

PubMed2005

Mammalian polyhomeotic homologues Phc2 and Phc1 act in synergy to mediate polycomb repression of Hox genes.

The Polycomb group (PcG) gene products form multimeric protein complexes and contribute to anterior-posterior (A-P) specification via the transcriptional regulation of Hox cluster genes. The Drosophila polyhomeotic genes and their mammalian orthologues, Phc1, Phc2, and Phc3, encode nuclear proteins that are constituents of evolutionarily conserved protein complexes designated class II PcG complexes. In this study, we describe the generation and phenotypes of Phc2-deficient mice. We show posterior transformations of the axial skeleton and premature senescence of mouse embryonic fibroblasts associated with derepression of Hox cluster genes and Cdkn2a genes, respectively. Synergistic actions of a Phc2 mutation with Phc1 and Rnf110 mutations during A-P specification, coimmunoprecipitation of their products from embryonic extracts, and chromatin immunoprecipitation by anti-Phc2 monoclonal antibodies suggest that Hox repression by Phc2 is mediated through the class II PcG complexes, probably via direct binding to the Hox locus. The genetic interactions further reveal the functional overlap between Phc2 and Phc1 and a strict dose-dependent requirement during A-P specification and embryonic survival. Functional redundancy between Phc2 and Phc1 leads us to hypothesize that the overall level of polyhomeotic orthologues in nuclei is a parameter that is critical in enabling the class II PcG complexes to exert their molecular functions.

Animals↗

PubMed2006

Alternative ESC and ESC-like subunits of a polycomb group histone methyltransferase complex are differentially deployed during Drosophila development.

The Extra sex combs (ESC) protein is a Polycomb group (PcG) repressor that is a key noncatalytic subunit in the ESC-Enhancer of zeste [E(Z)] histone methyltransferase complex. Survival of esc homozygotes to adulthood based solely on maternal product and peak ESC expression during embryonic stages indicate that ESC is most critical during early development. In contrast, two other PcG repressors in the same complex, E(Z) and Suppressor of zeste-12 [SU(Z)12], are required throughout development for viability and Hox gene repression. Here we describe a novel fly PcG repressor, called ESC-Like (ESCL), whose biochemical, molecular, and genetic properties can explain the long-standing paradox of ESC dispensability during postembryonic times. Developmental Western blots show that ESCL, which is 60% identical to ESC, is expressed with peak abundance during postembryonic stages. Recombinant complexes containing ESCL in place of ESC can methylate histone H3 with activity levels, and lysine specificity for K27, similar to that of the ESC-containing complex. Coimmunoprecipitations show that ESCL associates with E(Z) in postembryonic cells and chromatin immunoprecipitations show that ESCL tracks closely with E(Z) on Ubx regulatory DNA in wing discs. Furthermore, reduced escl+ dosage enhances esc loss-of-function phenotypes and double RNA interference knockdown of ESC/ESCL in wing disc-derived cells causes Ubx derepression. These results suggest that ESCL and ESC have similar functions in E(Z) methyltransferase complexes but are differentially deployed as development proceeds.

Amino Acid Sequence↗

PubMed2001

Coexpression of BMI-1 and EZH2 polycomb-group proteins is associated with cycling cells and degree of malignancy in B-cell non-Hodgkin lymphoma.

Polycomb-group (PcG) proteins, such as BMI-1 and EZH2, form multimeric gene-repressing complexes involved in axial patterning, hematopoiesis, and cell cycle regulation. In addition, BMI-1 is involved in experimental lymphomagenesis. Little is known about its role in human lymphomagenesis. Here, BMI-1 and EZH2 expression patterns are analyzed in a variety of B-cell non-Hodgkin lymphomas (B-NHLs), including small lymphocytic lymphoma, follicular lymphoma, large B-cell lymphoma, mantle-cell lymphoma, and Burkitt lymphoma. In contrast to the mutually exclusive pattern of BMI-1 and EZH2 in reactive follicles, the neoplastic cells in B-NHLs of intermediate- and high-grade malignancy showed strong coexpression of BMI-1 and EZH2. This pattern overlapped with the expression of Mib-1/Ki-67, a marker for proliferation. Neoplastic cells in B-NHL of low-grade malignancy were either BMI-1(low)/EZH2(+) (neoplastic centroblasts) or BMI-1(low)EZH2(-) (neoplastic centrocytes). These observations show that low-, intermediate-, and high grade B-NHLs are associated with increased coexpression of the BMI-1 and EZH2 PcG proteins, whose normal expression pattern is mutually exclusive. This expression pattern is probably caused by a failure to down-regulate BMI-1 in dividing neoplastic cells, because BMI-1 expression is absent from normal dividing B cells. These observations are in agreement with findings in studies of Bmi-1 transgenic mice. The extent of BMI-1/EZH2 coexpression correlated with clinical grade and the presence of Mib-1/Ki-67 expression, suggesting that the irregular expression of BMI-1 and EZH2 is an early event in the formation of B-NHL. This points to a role for abnormal PcG expression in human lymphomagenesis. (Blood. 2001;97:3896-3901)

Adolescent↗

PubMed2006

Corto and DSP1 interact and bind to a maintenance element of the Scr Hox gene: understanding the role of Enhancers of trithorax and Polycomb.

BACKGROUND: Polycomb-group genes (PcG) encode proteins that maintain homeotic (Hox) gene repression throughout development. Conversely, trithorax-group (trxG) genes encode positive factors required for maintenance of long term Hox gene activation. Both kinds of factors bind chromatin regions called maintenance elements (ME). Our previous work has shown that corto, which codes for a chromodomain protein, and dsp1, which codes for an HMGB protein, belong to a class of genes called the Enhancers of trithorax and Polycomb (ETP) that interact with both PcG and trxG. Moreover, dsp1 interacts with the Hox gene Scr, the DSP1 protein is present on a Scr ME in S2 cells but not in embryos. To understand better the role of ETP, we addressed genetic and molecular interactions between corto and dsp1. RESULTS: We show that Corto and DSP1 proteins co-localize at 91 sites on polytene chromosomes and co-immunoprecipitate in embryos. They interact directly through the DSP1 HMG-boxes and the amino-part of Corto, which contains a chromodomain. In order to search for a common target, we performed a genetic interaction analysis. We observed that corto mutants suppressed dsp11 sex comb phenotypes and enhanced AntpScx phenotypes, suggesting that corto and dsp1 are simultaneously involved in the regulation of Scr. Using chromatin immunoprecipitation of the Scr ME, we found that Corto was present on this ME both in Drosophila S2 cells and in embryos, whereas DSP1 was present only in S2 cells. CONCLUSION: Our results reveal that the proteins Corto and DSP1 are differently recruited to a Scr ME depending on whether the ME is active, as seen in S2 cells, or inactive, as in most embryonic cells. 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.

Animals↗

PubMed2006

Juxtaposed Polycomb complexes co-regulate vertebral identity.

Best known as epigenetic repressors of developmental Hox gene transcription, Polycomb complexes alter chromatin structure by means of post-translational modification of histone tails. Depending on the cellular context, Polycomb complexes of diverse composition and function exhibit cooperative interaction or hierarchical interdependency at target loci. The present study interrogated the genetic, biochemical and molecular interaction of BMI1 and EED, pivotal constituents of heterologous Polycomb complexes, in the regulation of vertebral identity during mouse development. Despite a significant overlap in dosage-sensitive homeotic phenotypes and co-repression of a similar set of Hox genes, genetic analysis implicated eed and Bmi1 in parallel pathways, which converge at the level of Hox gene regulation. Whereas EED and BMI1 formed separate biochemical entities with EzH2 and Ring1B, respectively, in mid-gestation embryos, YY1 engaged in both Polycomb complexes. Strikingly, methylated lysine 27 of histone H3 (H3-K27), a mediator of Polycomb complex recruitment to target genes, stably associated with the EED complex during the maintenance phase of Hox gene repression. Juxtaposed EED and BMI1 complexes, along with YY1 and methylated H3-K27, were detected in upstream regulatory regions of Hoxc8 and Hoxa5. The combined data suggest a model wherein epigenetic and genetic elements cooperatively recruit and retain juxtaposed Polycomb complexes in mammalian Hox gene clusters toward co-regulation of vertebral identity.

Animals↗

PubMed1992

Ten different Polycomb group genes are required for spatial control of the abdA and AbdB homeotic products.

Mutations in genes of the Polycomb (Pc) group cause abnormal segmental development due to ectopic expression of the homeotic products of the Antennapedia and bithorax complexes. Here the requirements for Pc group genes in controlling the abdA and AbdB products of the bithorax complex are described. 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), Posterior sex combs (Psc) and pleiohomeotic (pho) were examined. In every case, both abdA and AbdB are expressed outside of their normal domains along the anterior-posterior (A-P) axis, consistent with these Pc group products acting in a single pathway or molecular complex. The earliest detectable ectopic expression is highest in the parasegments immediately adjacent to the normal expression boundary. Surprisingly, in the most severe Pc group mutants, the earliest ectopic AbdB is distributed in a pair-rule pattern. At all stages, ectopic abdA in the epidermis is highest along the anterior edges of the parasegments, in a pattern that mimics the normal abdA cell-specific pattern. These examples of highly patterned mis-expression show that Pc group mutations do not cause indiscriminate activation of homeotic products. We suggest that the ectopic expression patterns result from factors that normally activate abdA and AbdB only in certain parasegments, but that in Pc group mutants these factors gain access to regulatory DNA in all parasegments.

Animals↗

PubMed1996

The Drosophila Enhancer of zeste gene encodes a chromosomal protein: examination of wild-type and mutant protein distribution.

The Drosophila Enhancer of zeste [E(z)] gene is a member of the Polycomb-group and, as such, is involved in maintaining the transcriptional repression of the homeotic genes of the Antennapedia (ANT-C) and bithorax (BX-C) complexes. It has been proposed that Polycomb-group (Pc-G)-mediated silencing requires the formation of heteromeric protein complexes which modify the chromatin structure of target genes. We describe the in vivo distribution of the E(Z) protein and show it to be ubiquitously present in embryonic and larval nuclei. In salivary gland polytenized nuclei, the identifiable E(Z) chromosome binding sites are a subset of those described for other Polycomb-group proteins, suggesting that E(Z) may also participate in Polycomb-group complexes. E(Z) binds to chromosomes in a DNA sequence-dependent manner, as illustrated by the creation of a new E(Z)-binding site at the location of a P element reporter construct that previously has been shown to contain a Polycomb response element (PRE). We also present the sequences of one null and three temperature-sensitive E(z) alleles, describe the effects these mutations have on the in vivo distribution of E(Z) protein and discuss their implications concerning putative functional domains. Finally, we describe the effect a trithorax mutation has on E(Z) chromosome binding.

Animals↗

PubMed1998

The Polycomb group in Caenorhabditis elegans and maternal control of germline development.

Four Caenorhabditis elegans genes, mes-2, mes-3, mes-4 and mes-6, are essential for normal proliferation and viability of the germline. Mutations in these genes cause a maternal-effect sterile (i.e. mes) or grandchildless phenotype. We report that the mes-6 gene is in an unusual operon, the second example of this type of operon in C. elegans, and encodes the nematode homolog of Extra sex combs, a WD-40 protein in the Polycomb group in Drosophila. mes-2 encodes another Polycomb group protein (see paper by Holdeman, R., Nehrt, S. and Strome, S. (1998). Development 125, 2457-2467). Consistent with the known role of Polycomb group proteins in regulating gene expression, MES-6 is a nuclear protein. It is enriched in the germline of larvae and adults and is present in all nuclei of early embryos. Molecular epistasis results predict that the MES proteins, like Polycomb group proteins in Drosophila, function as a complex to regulate gene expression. Database searches reveal that there are considerably fewer Polycomb group genes in C. elegans than in Drosophila or vertebrates, and our studies suggest that their primary function is in controlling gene expression in the germline and ensuring the survival and proliferation of that tissue.

Amino Acid Sequence↗

PubMed1998

The Drosophila Polycomb Group proteins ESC and E(Z) bind directly to each other and co-localize at multiple chromosomal sites.

The Polycomb Group gene esc encodes an evolutionarily conserved protein required for transcriptional silencing of the homeotic genes. Unlike other Polycomb Group genes, esc is expressed and apparently required only during early embryogenesis, suggesting it is required for the initial establishment of silencing but not for its subsequent maintenance. We present evidence that the ESC protein interacts directly with E(Z), another Polycomb Group protein required for silencing of the homeotic genes. We show that the most highly conserved region of ESC, containing seven WD motifs that are predicted to fold into a beta-propeller structure, mediate its binding to a conserved N-terminal region of E(Z). Mutations in the WD region that perturb ESC silencing function in vivo also perturb binding to E(Z) in vitro. The entire WD region forms a trypsin-resistant structure, like known beta -propeller domains, and mutations that would affect the predicted ESC beta-propeller perturb its trypsin-resistance, while a putative structure-conserving mutation does not. We show by co-immunoprecipitation that ESC and E(Z) are directly associated in vivo and that they also co-localize at many chromosomal binding sites. Since E(Z) is required for binding of other Polycomb Group proteins to chromosomes, these results suggest that formation of an E(Z):ESC complex at Polycomb Response Elements may be an essential prerequisite for the establishment of silencing.

Amino Acid Sequence↗

PubMed1998

The Polycomb-group gene eed is required for normal morphogenetic movements during gastrulation in the mouse embryo.

We have characterized an induced mutation, called embryonic ectoderm development or eed, that disrupts A-P patterning of the mouse embryo during gastrulation. Positional cloning of this gene revealed it to be the highly conserved homologue of the Drosophila gene extra sex combs, which is required for maintenance of long-term transcriptional repression of homeotic gene expression. Mouse embryos homozygous for loss-of-function alleles of eed initiate gastrulation but display abnormal mesoderm production. Very little embryonic mesoderm is produced; in contrast, extraembryonic mesoderm is relatively abundant. These observations, along with mRNA in situ hybridization analyses, suggested a defect in the anterior primitive streak, from which much of the embryonic mesoderm of the wild-type embryo is derived. To analyse this defect, we initiated clonal analysis of the pre-streak epiblast in eed mutant embryos, using the lineage tracer horseradish peroxidase (HRP). The results of these studies indicate that epiblast cells ingress through the anterior streak, but the newly formed mesoderm does not migrate anteriorly and is mislocalized to the extraembryonic compartment. Abnormal localization of mesoderm to the extraembryonic region did not appear to be due to a restriction and alteration of distal epiblast cell fate, since the majority of clones produced from regions fated to ingress through the anterior streak were mixed, displaying descendants in both embryonic and extraembryonic derivatives. eed mutant embryos also fail to display proper epiblast expansion, particularly with respect to the A-P axis. Based on patterns of clonal spread and calculated clone doubling times for the epiblast, this does not appear to be due to decreased epiblast growth. Rather, epiblast, which is normally fated to make a substantial contribution to the axial midline, appears to make mesoderm preferentially. The data are discussed in terms of global morphogenetic movements in the mouse gastrula and a disruption of signalling activity in the anterior primitive streak.

Animals↗

PubMed2001

Su(z)12, a novel Drosophila Polycomb group gene that is conserved in vertebrates and plants.

In both Drosophila and vertebrates, spatially restricted expression of HOX genes is controlled by the Polycomb group (PcG) repressors. Here we characterize a novel Drosophila PcG gene, Suppressor of zeste 12 (Su(z)12). Su(z)12 mutants exhibit very strong homeotic transformations and Su(z)12 function is required throughout development to maintain the repressed state of HOX genes. Unlike most other PcG mutations, Su(z)12 mutations are strong suppressors of position-effect variegation (PEV), suggesting that Su(z)12 also functions in heterochromatin-mediated repression. Furthermore, Su(z)12 function is required for germ cell development. The Su(z)12 protein is highly conserved in vertebrates and is related to the Arabidopsis proteins EMF2, FIS2 and VRN2. Notably, EMF2 is a repressor of floral homeotic genes. These results suggest that at least some of the regulatory machinery that controls homeotic gene expression is conserved between animals and plants.

Amino Acid Sequence↗