Multitasking with ubiquitin through multivalent interactions.

Ubiquitylation - the post-translational modification of proteins with ubiquitin - serves powerful regulatory roles in eukaryotes. It can label proteins for destruction or activate gene transcription. Despite its versatility, ubiquitin is used to signal for cellular events with exquisite specificity. To achieve both versatility and specificity, ubiquitin signaling pathways use multivalency, namely the coordinated use of multiple interaction surfaces. Multivalent interactions regulate each stage of ubiquitin signaling pathways, and appear within the ubiquitin signal, the ubiquitylated substrate, ubiquitin processing enzymes and ubiquitin recognition proteins. Copyright 2010 Elsevier Ltd. All rights reserved.