title: An epididymal form of cauxin, a carboxylesterase-like enzyme, is present and active in mammalian male reproductive fluids.
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.
authors.affiliation: Gamètes Males et Fertilité, 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.
authors.forename: Heath
authors.initials: H
authors.lastname: Ecroyd
authors.forename: Maya
authors.initials: M
authors.lastname: Belghazi
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Dacheux
authors.forename: Masao
authors.initials: M
authors.lastname: Miyazaki
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Yamashita
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Gatti
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001826:Body Fluids / Q000201:enzymology*; D043182:Carboxylesterase / Q000235:genetics* / Q000378:metabolism*; D002415:Cats; D004822:Epididymis / Q000201:enzymology*; D008297:Male; D008322:Mammals; D051379:Mice; D008969:Molecular Sequence Data; D011328:Prions / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D012661:Semen / Q000201:enzymology; D017386:Sequence Homology, Amino Acid; D012756:Sheep; D013552:Swine
chemical_list: D011328:Prions; D012333:RNA, Messenger; D043182:Carboxylesterase