BACKGROUND: Thioredoxins (Trx) are small redox proteins that function as general protein disulphide reductases and regulate several cellular processes such as transcription factor DNA binding activity, apoptosis and DNA synthesis. In mammalian organisms, thioredoxins are generally ubiquitously expressed in all tissues, with the exception of Sptrx-1 which is specifically expressed in sperm cells. RESULTS: We report here the identification and characterization of a novel member of the thioredoxin family, the second with a tissue-specific distribution in human sperm, termed Sptrx-2. The Sptrx-2 ORF (open reading frame) encodes for a protein of 588 amino acids with two different domains: an N-terminal thioredoxin domain encompassing the first 105 residues and a C-terminal domain composed of three repeats of a NDP kinase domain. The Sptrx-2 gene spans about 51 kb organized in 17 exons and maps at locus 7p13-14. Sptrx-2 mRNA is exclusively expressed in human testis, mainly in primary spermatocytes, while Sptrx-2 protein expression is detected from the pachytene spermatocytes stage onwards, peaking at round spermatids stage. Recombinant full-length Sptrx-2 expressed in bacteria displayed neither thioredoxin nor NDP kinase enzymatic activity. CONCLUSIONS: The sperm specific expression of Sptrx-2, together with its chromosomal assignment to a position reported as a potential locus for flagellar anomalies and male infertility phenotypes such as primary ciliary dyskinesia, suggests that it might be a novel component of the human sperm axonemal organization.

This article has been cited by other articles:

				P. Dammeyer, A. E. Damdimopoulos, T. Nordman, A. Jimenez, A. Miranda-Vizuete, and E. S. J. Arner Induction of Cell Membrane Protrusions by the N-terminal Glutaredoxin Domain of a Rare Splice Variant of Human Thioredoxin Reductase 1 J. Biol. Chem., February 1, 2008; 283(5): 2814 - 2821. [Abstract] [Full Text] [PDF]

				B. Duriez, P. Duquesnoy, E. Escudier, A.-M. Bridoux, D. Escalier, I. Rayet, E. Marcos, A.-M. Vojtek, J.-F. Bercher, and S. Amselem A common variant in combination with a nonsense mutation in a member of the thioredoxin family causes primary ciliary dyskinesia PNAS, February 27, 2007; 104(9): 3336 - 3341. [Abstract] [Full Text] [PDF]

				K.-i. Wakabayashi and S. M. King Modulation of Chlamydomonas reinhardtii flagellar motility by redox poise J. Cell Biol., June 5, 2006; 173(5): 743 - 754. [Abstract] [Full Text] [PDF]

				G. Parra, A. Reymond, N. Dabbouseh, E. T. Dermitzakis, R. Castelo, T. M. Thomson, S. E. Antonarakis, and R. Guigo Tandem chimerism as a means to increase protein complexity in the human genome Genome Res., January 1, 2006; 16(1): 37 - 44. [Abstract] [Full Text] [PDF]

				G J Pazour, N Agrin, B L Walker, and G B Witman Identification of predicted human outer dynein arm genes: candidates for primary ciliary dyskinesia genes J. Med. Genet., January 1, 2006; 43(1): 62 - 73. [Abstract] [Full Text] [PDF]

				D. Su, S. V. Novoselov, Q.-A. Sun, M. E. Moustafa, Y. Zhou, R. Oko, D. L. Hatfield, and V. N. Gladyshev Mammalian Selenoprotein Thioredoxin-glutathione Reductase: ROLES IN DISULFIDE BOND FORMATION AND SPERM MATURATION J. Biol. Chem., July 15, 2005; 280(28): 26491 - 26498. [Abstract] [Full Text] [PDF]

				A. Jimenez, W. Zu, V. Y. Rawe, M. Pelto-Huikko, C. J. Flickinger, P. Sutovsky, J.-A. Gustafsson, R. Oko, and A. Miranda-Vizuete Spermatocyte/Spermatid-specific Thioredoxin-3, a Novel Golgi Apparatus-associated Thioredoxin, Is a Specific Marker of Aberrant Spermatogenesis J. Biol. Chem., August 13, 2004; 279(33): 34971 - 34982. [Abstract] [Full Text] [PDF]

				R. S. Patel-King, O. Gorbatyuk, S. Takebe, and S. M. King Flagellar Radial Spokes Contain a Ca2+-stimulated Nucleoside Diphosphate Kinase Mol. Biol. Cell, August 1, 2004; 15(8): 3891 - 3902. [Abstract] [Full Text] [PDF]

				H.-J. Shi, A. Z. Wu, M. Santos, Z.-M. Feng, L. Huang, Y.-M. Chen, K. Zhu, and C.-L. C. Chen Cloning and Characterization of Rat Spermatid Protein SSP411: A Thioredoxin-Like Protein J Androl, July 1, 2004; 25(4): 479 - 493. [Abstract] [Full Text] [PDF]

				J. Jurado, M.-J. Prieto-Alamo, J. Madrid-Risquez, and C. Pueyo Absolute Gene Expression Patterns of Thioredoxin and Glutaredoxin Redox Systems in Mouse J. Biol. Chem., November 14, 2003; 278(46): 45546 - 45554. [Abstract] [Full Text] [PDF]

				A. Miranda-Vizuete, K. Tsang, Y. Yu, A. Jimenez, M. Pelto-Huikko, C. J. Flickinger, P. Sutovsky, and R. Oko Cloning and Developmental Analysis of Murid Spermatid-specific Thioredoxin-2 (SPTRX-2), a Novel Sperm Fibrous Sheath Protein and Autoantigen J. Biol. Chem., November 7, 2003; 278(45): 44874 - 44885. [Abstract] [Full Text] [PDF]

				C. M. Sadek, A. Jimenez, A. E. Damdimopoulos, T. Kieselbach, M. Nord, J.-A. Gustafsson, G. Spyrou, E. C. Davis, R. Oko, F. A. van der Hoorn, et al. Characterization of Human Thioredoxin-like 2. A NOVEL MICROTUBULE-BINDING THIOREDOXIN EXPRESSED PREDOMINANTLY IN THE CILIA OF LUNG AIRWAY EPITHELIUM AND SPERMATID MANCHETTE AND AXONEME J. Biol. Chem., April 4, 2003; 278(15): 13133 - 13142. [Abstract] [Full Text] [PDF]

				R. S. Patel-King, S. E. Benashski, and S. M. King A Bipartite Ca2+-regulated Nucleoside-diphosphate Kinase System within the Chlamydomonas Flagellum. THE REGULATORY SUBUNIT p72 J. Biol. Chem., September 6, 2002; 277(37): 34271 - 34279. [Abstract] [Full Text] [PDF]

				A. Jimenez, R. Oko, J.-A. Gustafsson, G. Spyrou, M. Pelto-Huikko, and A. Miranda-Vizuete Cloning, expression and characterization of mouse spermatid specific thioredoxin-1 gene and protein Mol. Hum. Reprod., August 1, 2002; 8(8): 710 - 718. [Abstract] [Full Text] [PDF]