JAB1/CSN5 interacts with the GAL4 DNA binding domain: a note of caution about two-hybrid interactions

Biochimie. 2001 Oct;83(10):969-71. doi: 10.1016/s0300-9084(01)01329-3.


The Jun activation domain binding protein 1 (JAB1) was first identified as an interaction partner and coactivator of c-Jun. Subsequently, it was found to be a subunit of the COP9 signalosome (CSN) and termed CSN subunit 5 (CSN5). This complex regulates light-mediated development in plants and plays an essential role in a variety of organisms. A striking feature of JAB1/CSN5 is its reported interaction with a wide range of proteins and its modulation of their activity or stability. We applied the yeast two-hybrid system to screen for proteins interacting with the DNA-binding domain of the transcription factor c-Myb and found JAB1/CSN5 among the double-positive clones. To our surprise JAB1/CSN5 was shown to interact with the DNA-binding domain of GAL4 alone and had to be rejected as a false positive in the GAL4-based two-hybrid system. This finding emphasizes the necessity of particular caution when JAB1/CSN5 is found in two-hybrid screenings.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bone Marrow
  • COP9 Signalosome Complex
  • DNA / metabolism
  • DNA-Binding Proteins / metabolism*
  • False Positive Reactions
  • Fungal Proteins / chemistry
  • Fungal Proteins / metabolism*
  • Gene Library
  • Humans
  • Intracellular Signaling Peptides and Proteins
  • Peptide Hydrolases
  • Protein Structure, Tertiary
  • Proto-Oncogene Proteins c-myb / metabolism*
  • Recombinant Fusion Proteins / metabolism
  • Saccharomyces cerevisiae Proteins*
  • Transcription Factors / chemistry
  • Transcription Factors / metabolism*
  • Two-Hybrid System Techniques
  • Yeasts


  • DNA-Binding Proteins
  • Fungal Proteins
  • GAL4 protein, S cerevisiae
  • Intracellular Signaling Peptides and Proteins
  • Proto-Oncogene Proteins c-myb
  • Recombinant Fusion Proteins
  • Saccharomyces cerevisiae Proteins
  • Transcription Factors
  • DNA
  • Peptide Hydrolases
  • COPS5 protein, human
  • COP9 Signalosome Complex