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This Article Full Text Full Text (PDF) All Versions of this Article: 74/2/439    most recent biolreprod.105.046847v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Ecroyd, H. Articles by Gatti, J.-L. Search for Related Content PubMed PubMed Citation Articles by Ecroyd, H. Articles by Gatti, J.-L. Agricola Articles by Ecroyd, H. Articles by Gatti, J.-L.

An Epididymal Form of Cauxin, a Carboxylesterase-Like Enzyme, Is Present and Active in Mammalian Male Reproductive Fluids¹

Gamètes Males et Fertilité,⁴ Service de spectrométrie de masse pour la protéomique,⁵ UMR 6175 INRA-CNRS-Université de Tours-Haras Nationaux, Station de Physiologie de la Reproduction et des Comportements, Institut National de la Recherche Agronomique, INRA-Nouzilly, 37380 Monnaie, France Department of Agro-bioscience,⁶ Faculty of Agriculture, Iwate University, Morioka 020-8550, Japan

ABSTRACT

Mass spectrometric analysis of a prion protein (PrP)-containing complex isolated from ram cauda epididymal fluid revealed a protein that showed homology to a carboxylesterase-like protein previously identified in cat urine (cauxin). Using anti-cauxin antibodies, immunoreactive bands were detected in corpus and cauda epididymal fluid from all mammals tested (ram, boar, mouse, and cat). In the ram, the protein was also present in seminal fluid but not found to be associated with sperm. The bands reacting with the anti-cauxin antibody coincided with those having esterase activity in a zymographic assay and its levels paralleled the esterase activity of native epididymal fluids. A partial nucleotide sequence of 1143 bp, corresponding to 380 amino acids, was obtained by RT-PCR amplification from total RNA from the corpus epididymis (zone 6). The deduced protein sequence shows a high degree of homology (up to 90%) with the different cauxin proteins found in databases but only up to 60% with other known carboxylesterases. By PCR, strong mRNA expression was found in the corpus and cauda epididymis, while the testis, kidney, and caput epididymis had low expression. No mRNA was detected in the lung, heart, or liver. These data demonstrate that an epididymal form of the cauxin enzyme is secreted into mammalian epididymal fluid. In the ram, it is associated with a high molecular-weight PrP-associated complex and may be responsible for the majority of the esterase activity in the cauda epididymal fluid of this species.

epididymis, male reproductive tract, sperm maturation

¹ Supported by the Région Centre, GIS Prion, and GIS Génanimal. H.E. was the holder of a postdoctoral grant cofinanced by the Région Centre, the Département de Physiologie Animale et Système d'Elevage de l'INRA, and the CNRS.

² Correspondence. FAX: 33 247 427 743; gatti{at}tours.inra.fr

³ Current address: School of Chemistry and Physics, University of Adelaide, 5005 SA, Australia.