Degradation of FAT10 by the 26S proteasome is independent of ubiquitylation but relies on NUB1L

FEBS Lett. 2009 Feb 4;583(3):591-4. doi: 10.1016/j.febslet.2009.01.006. Epub 2009 Jan 21.


The ubiquitin-like modifier FAT10 targets proteins for degradation by the proteasome, a process accelerated by the UBL-UBA domain protein NEDD8 ultimate buster 1-long. Here, we show that FAT10-mediated degradation occurs independently of poly-ubiquitylation as purified 26S proteasome readily degraded FAT10-dihydrofolate reductase (DHFR) but not ubiquitin-DHFR in vitro. Interestingly, the 26S proteasome could only degrade FAT10-DHFR when NUB1L was present. Knock-down of NUB1L attenuated the degradation of FAT10-DHFR in intact cells suggesting that NUB1L determines the degradation rate of FAT10-linked proteins. In conclusion, our data establish FAT10 as a ubiquitin-independent but NUB1L-dependent targeting signal for proteasomal degradation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • HeLa Cells
  • Humans
  • Proteasome Endopeptidase Complex / metabolism*
  • Protein Binding
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Ubiquitination
  • Ubiquitins / genetics
  • Ubiquitins / metabolism*


  • Transcription Factors
  • Ubiquitins
  • Proteasome Endopeptidase Complex
  • ATP dependent 26S protease