TIP120A associates with cullins and modulates ubiquitin ligase activity

Kyoeng Woo Min, Ji Won Hwang, Jong Sik Lee, Yoon Park, Taka aki Tamura, Jong Bok Yoon

Research output: Contribution to journalArticle

62 Citations (Scopus)

Abstract

The cullin-containing ubiquitin-protein isopeptide ligases (E3s) play an important role in regulating the abundance of key proteins involved in cellular processes such as cell cycle and cytokine signaling. They have multisubunit modular structures in which substrate recognition and the catalysis of ubiquitination are carried out by distinct polypeptides. In a search for proteins involved in regulation of cullin-containing E3 ubiquitin ligases we immunopurified CUL4B-containing complex from HeLa cells and identified TIP120A as an associated protein by mass spectrometry. Immunoprecipitation of cullins revealed that all cullins tested specifically interacted with TIP120A. Reciprocal immunoaffinity purification of TIP120A confirmed the stable interaction of TIP120A with cullin family proteins. TIP120A formed a complex with CUL1 and Rbx1, but interfered with the binding of Skp1 and F-box proteins to CUL1. TIP120A greatly reduced the ubiquitination of phosphorylated IκBα by SCFβ-TrCP ubiquitin ligase. These results suggest that TIP120A functions as a negative regulator of SCF E3 ubiquitin ligases and may modulate other cullin ligases in a similar fashion.

Original languageEnglish
Pages (from-to)15905-15910
Number of pages6
JournalJournal of Biological Chemistry
Volume278
Issue number18
DOIs
Publication statusPublished - 2003 May 2

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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