Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

View full-text article in PMC

. 2014 Mar 26;4(3):140006. doi: 10.1098/rsob.140006

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

© 2014 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0/, which permits unrestricted use, provided the original author and source are credited.

PMC Copyright notice

Figure 3. — PcG complexes, PRE architecture and pairing-sensitive silencing (PSS). (a) Multiple polycomb group complexes have been characterized: Polycomb Repressive Complex 1 and 2 (PRC1, PRC2), Pho-repressive complex (PhoRC), dRING-associated factors (dRAF) and Polycomb repressive deubiquitinase (PR-DUB). E(z) catalyses trimethylation of histone 3 on lysine 27 (H3K27me3). The chromodomain of Pc is known to recognize this mark. Pho (and the related Phol) are the only PcG proteins to have characterized sequence-specific binding. dRING (also called Sce, Sex combs extra) catalyses H2A ubiquitination in the context of the dRAF complex, but not in the context of PRC1. The PR-DUB complex removes this H2A ubiquitination. The reason for ubiquitination cycling on H2A is not fully understood. Adapted from Schwartz & Pirrotta [53]. (b) The engrailed PREs and the iab-7/Fab-7 PRE are schematized with identified consensus sequences for various DNA-binding factors. Despite the large number of potential interactors, no single motif is sufficient to predict PREs. Adapted from Brown & Kassis [54]. (c) PSS is a phenomenon in which expression of a homozygous transgene that contains a PRE is less than in the heterozygous case, suggesting that homologue pairing enhances silencing mediated by the PRE. In comparison, homozygosity for transgenes lacking PREs generally leads to higher expression levels. The gradation of expression is schematized for a mini-white transgene in a white^–/− genetic background. The white gene is responsible for red eye colour in flies.