title: The Polycomb-associated protein Rybp is a ubiquitin binding protein.
abstract: The Rybp protein has been promoted as a Polycomb group (PcG)-associated protein, but its molecular function has remained elusive. Here we show that Rybp is a novel ubiquitin binding protein and is itself ubiquitinated. The Rybp interacting PcG protein Ring1B, a known ubiquitin E3 ligase, promotes Rybp ubiquitination. Moreover, one target of Rybp's ubiquitin binding domain appears to be ubiquitinated histone H2A; this histone is a substrate for Ring1B's E3 ligase activity in association with gene silencing processes. These findings on Rybp provide a further link between the ubiquitination system and PcG transcriptional repressors.
authors.affiliation: Department of Molecular Genetics, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Ullmann 809 Bronx, NY 10461, USA. rachele.arrigoni@med.nyu.edu
authors.forename: Rachele
authors.initials: R
authors.lastname: Arrigoni
authors.forename: Steven L
authors.initials: SL
authors.lastname: Alam
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Wamstad
authors.forename: Vivian J
authors.initials: VJ
authors.lastname: Bardwell
authors.forename: Wesley I
authors.initials: WI
authors.lastname: Sundquist
authors.forename: Nicole
authors.initials: N
authors.lastname: Schreiber-Agus
mesh_terms: D000818:Animals; D020868:Gene Silencing; D006657:Histones / Q000378:metabolism; D051379:Mice; D063146:Polycomb-Group Proteins; D011485:Protein Binding; D012097:Repressor Proteins / Q000378:metabolism* / Q000502:physiology; D025801:Ubiquitin / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism; D016335:Zinc Fingers
chemical_list: D006657:Histones; D063146:Polycomb-Group Proteins; D012097:Repressor Proteins; C120616:Rybp protein, mouse; D025801:Ubiquitin; D044767:Ubiquitin-Protein Ligases