Characterization of a novel, testis-specific equine serine/threonine kinase

Khalida Sabeur, Barry A. Ball, C. Jo Corbin, Alan Conley

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


Testis-specific protein kinases are important because of their potential role in spermiogenesis, sperm maturation, and sperm function. In the present study, a novel serine-threonine kinase with high identity to human serine-threonine kinase 31 (STK31) was cloned from equine testis and expression of the protein was characterized in equine testis and ejaculated spermatozoa. Five over-lapping independent clones were plaque purified after screening of a λ ZAP cDNA expression library constructed from equine testis. Sequence analysis and alignment of all five clones showed high identity with human STK31 with approximately 200 bp of the equine N-terminal sequence incomplete. The putative full-length coding sequence of this testis specific equine cDNA was completed by amplification of a 200-bp fragment using a human primer upstream of the reported translational start site with equine specific nested primers. Northern blot analysis using the equine STK31 cDNA detected an RNA transcript of ∼3.1 kb present in testis but not in other reproductive or somatic tissues. Immunolocalization of the protein in equine testis and spermatozoa demonstrated that STK31 was present in post-meiotic germ cells with localization to the equatorial segment of testicular spermatozoa. Analysis of the domain structure of equine STK31 revealed a protein kinase domain along with a putative RNA-binding region. The post-meiotic expression of this protein along with its domain structure suggests that STK31 may have a role in reorganization of sperm chromatin during spermiogenesis. The cloning of this novel, testis-specific equine STK provides a new tool to explore the role of kinases in sperm function.

Original languageEnglish
Pages (from-to)867-873
Number of pages7
JournalMolecular Reproduction and Development
Issue number5
StatePublished - May 2008


  • Horse
  • Serine-threonine kinase
  • Spermatozoa
  • Testis

ASJC Scopus subject areas

  • Genetics
  • Developmental Biology
  • Cell Biology


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