The Polycomb-group gene, extra sex combs, encodes a nuclear member of the WD-40 repeat family.

Abstract

We have delimited the extra sex combs (esc) gene to < 4 kb that include a single transcript and are able to rescue both the maternal and zygotic esc phenotypes. Several mutations have been identified within the esc transcript. In agreement with earlier genetic studies, esc is expressed maternally and its product is most abundant during the early embryonic stages. It encodes a protein of the WD‐40 repeat family, which localizes predominantly to the nucleus. During germ band extension, it is expressed in a stereotypic pattern of neuroblasts. We propose a model in which Esc is recruited by gap proteins both to act as a corepressor that competes with the TAFII80 coactivator to block transcription and also to mediate the transition to permanent repression by Polycomb‐group proteins.

HEED, the Product of the Human Homolog of the Murineeed Gene, Binds to the Matrix Protein of HIV-1

“…As already reported for mouse EED, a specific feature of the HEED protein was the occurrence of several repeats of the module GH-(30 -40 residue spacer)-WD (46), now simply referred to as WD repeat motif (47). In HEED (Fig.…”

Mutations in the FIE and MEA Genes That Encode Interacting Polycomb Proteins Cause Parent-of-Origin Effects on Seed Development by Distinct Mechanisms

“…Initially recruited, although not in a direct interaction (Kehle et al, 1998; Zhang et al, 1998), by a zinc finger transcription factor (HUNCHBACK), ESC functions transiently (Struhl and Brower, 1992;Gutjahr et al, 1995;Sathe and Harte, 1995) to recruit other polycomb group proteins, including the SET domain protein E(Z), which form large, stable complexes at specific sites within the genome (Sewalt et al, 1998;van der Vlag and Otte, 1999;Ng et al, 2000). The complexes, perhaps by the action of a histone deacetylase component (van der Vlag and Otte, 1999), are thought to remodel chromatin into a condensed form that prevents gene transcription (Pirrotta, 1998).…”

“…The Drosophila and mouse WD and SET domain polycomb proteins have a somatic role and control pattern formation during embryogenesis by suppressing the transcription of homeotic genes (Gutjahr et al, 1995;Schumacher et al, 1996). In contrast, the Caenorhabditis WD and SET domain homologs MES6 and MES2, respectively, act as transcriptional repressors (Kelly and Fire, 1998) and are essential for germ line development (Holdemann et al, 1998;Korf et al, 1998).…”

“…The FIE polypeptide has seven tryptophan-aspartate (WD) motifs (Ng et al, 1997). FIE is related to polycomb proteins from Drosophila ( EXTRA SEX COMBS [ ESC ; Gutjahr et al, 1995;Sathe and Harte, 1995]), mammals ( EM-BRYONIC ECTODERM DEVELOPMENT [ EED ; Schumacher et al, 1996;Sewalt et al, 1998]), and Caenorhabditis ( MA-TERNAL EFFECT STERILE6 [ MES6 ; Korf et al, 1998]). Drosophila ESC and mammalian EED promote interactions with other polycomb proteins that repress gene transcription at specific sites within the genome (Wall et al, 1995;Sondek et al, 1996;Ng et al, 1997).…”

A Complex Composed of Tup1 and Ssn6 Represses Transcription in Vitro

“…However, an increasing number of WD repeat proteins have been identified that are nuclear localized and function in the repression of transcription. These include Tup1, Hir1, and Met30 in S. cerevisiae; SCON2 in Neurospora crassa; extra sex combs and groucho in Drosophila; COP1 in Arabidopsis thaliana; and HIRA and the family of TLE proteins in humans (1)(2)(3)(4)(5)(6)(7)(8)(9)(10). These WD repeat repressor proteins turn off a wide variety of genes, including those involved in segmentation, sex determination, and neurogenesis (controlled by groucho) and those involved in photomorphogenesis (controlled by COP1) (7,11).…”