False positives in MALDI-TOF detection of ERβ in mitochondria

Thomas Schwend, Jan Åke Gustafsson

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


Recently, Yang et al. reported that estrogen receptor beta (ERβ) is a mitochondrial protein rather than a nuclear receptor. Because this claim would lead to a significant change in our understanding of estrogen signaling, we have attempted to reproduce the MALDI-TOF data of Yang et al. We separated proteins extracted from mouse liver mitochondria by SDS-PAGE and analysed a gel band covering the molecular weight range of 50-65 kDa by MALDI-TOF/TOF. Analysis of the data with the MASCOT database algorithm provided no evidence for the presence of ERβ in the mitochondria. If we search (as the authors did) with only the peptide masses which match to tryptic fragments of ERβ, ERβ is identified with a significant score of 69. However, fragmentation of these peptides shows that they are not from ERβ. Our conclusion is that ERβ cannot be identified by MALDI-TOF from a mixture of mitochondrial proteins resolved on SDS-PAGE.

Original languageEnglish (US)
Pages (from-to)707-711
Number of pages5
JournalBiochemical and Biophysical Research Communications
Issue number3
StatePublished - May 12 2006


  • Estrogen receptor beta
  • False positive
  • Mitochondria

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology


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