Human spermatid-specific thioredoxin-1 (Sptrx-1) is a two-domain protein with oxidizing activity

Alberto Jiménez, Catrine Johansson, Johanna Ljung, Johan Sagemark, Kurt D. Berndt, Bin Ren, Gudrun Tibbelin, Rudolf Ladenstein, Thomas Kieselbach, Arne Holmgren, Jan Åke Gustafsson, Antonio Miranda-Vizuete

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


Spermatid-specific thioredoxin-1 (Sptrx-1) is the first member of the thioredoxin family of proteins with a tissue-specific expression pattern, found exclusively in the tail of elongating spermatids and spermatozoa. We describe here further biochemical characterization of human Sptrx-1 protein structure and enzymatic activity. In gel filtration chromatography human Sptrx-1 eluates as a 400 kDa protein consistent with either an oligomeric form, not maintained by intermolecular disulfide bonding, and/or a highly asymmetrical structure. Analysis of circular dichroism spectra of fragments 1-360 and 361-469 and comparison to spectra of full-length Sptrx-1 supports a two-domain organization with a largely unstructured N-terminal domain and a folded thioredoxin-like C-terminal domain. Functionally, Sptrx-1 behaves as an oxidant in vitro when using selenite, but not oxidized glutathione, as electron acceptor. This oxidizing enzymatic activity suggests that Sptrx-1 might govern the stabilization (by disulfide cross-linking) of the different structures in the developing tail of spermatids and spermatozoa.

Original languageEnglish (US)
Pages (from-to)79-84
Number of pages6
JournalFEBS Letters
Issue number1-3
StatePublished - Oct 23 2002


  • Fibrous sheath
  • Redox regulation
  • Spermatozoon
  • Thioredoxin

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology


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