Human spermatid-specific thioredoxin-1 (Sptrx-1) is a two-domain protein with oxidizing activity
Abstract
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.
- Publication:
-
FEBS Letters
- Pub Date:
- January 2002
- DOI:
- 10.1016/S0014-5793(02)03417-8
- Bibcode:
- 2002FEBSL.530...79J
- Keywords:
-
- Thioredoxin;
- Spermatozoon;
- Fibrous sheath;
- Redox regulation;
- FS;
- fibrous sheath;
- ODF;
- outer dense fibers;
- PDI;
- protein disulfide isomerase;
- Trx-1;
- -2;
- thioredoxin-1;
- -2