MUF1, A Novel Elongin BC-interacting Leucine-rich Repeat Protein That Can Assemble with Cul5 and Rbx1 to Reconstitute a Ubiquitin Ligase

Takumi Kamura, Dennis Burian, Qin Yan, Susan L. Schmidt, William S. Lane, Emmanuelle Querido, Philip E. Branton, Ali Shilatifard, Ronald C. Conaway, Joan Weliky Conaway*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

126 Scopus citations

Abstract

The heterodimeric Elongin BC complex has been shown to interact in vitro and in mammalian cells with a conserved BC-box motif found in a growing number of proteins including RNA polymerase II elongation factor Elongin A, SOCS-box proteins, and the von Hippel-Lindau (VHL) tumor suppressor protein. Recently, the VHL-Elongin BC complex was found to interact with a module composed of Cullin family member Cul2 and RING-H2 finger protein Rbxl to reconstitute a novel E3 ubiquitin ligase that activates ubiquitylation by the E2 ubiquitin-conjugating enzymes Ubc5 and Cdc34. In the context of the VHL ubiquitin ligase, Elongin BC functions as an adaptor that links the VHL protein to the Cul2/Rbx1 module, raising the possibility that the Elongin BC complex could function as an integral component of a larger family of E3 ubiquitin ligases by linking alternative BC-box proteins to Cullin/Rbx1 modules. In this report, we describe identification and purification from rat liver of a novel leucine-rich repeat-containing BC-box protein, MUF1, which we demonstrate is capable of assembling with a Cullin/Rbxl module containing the Cullin family member Cul5 to reconstitute ubiquitin ligase activity. In addition, we show that the additional BC-box proteins Elongin A, SOCS1, and WSB1 are also capable of assembling with the Cul5/Rbxl module to reconstitute potential ubiquitin ligases. Taken together, our findings identify MUF1 as a new member of the BC-box family of proteins, and they predict the existence of a larger family of Elongin BC-based E3 ubiquitin ligases.

Original languageEnglish (US)
Pages (from-to)29748-29753
Number of pages6
JournalJournal of Biological Chemistry
Volume276
Issue number32
DOIs
StatePublished - Aug 10 2001

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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