tailieunhanh - Báo cáo khoa học: Characterization of a membrane-bound angiotensin-converting enzyme isoform in crayfish testis and evidence for its release into the seminal fluid

In the present study, an isoform of angiotensin-converting enzyme was characterized from the testis of a decapod crustacean, the crayfish Asta-cus leptodactylus. Angiotensin-converting enzyme cDNA, obtained by 3¢-to5¢ RACE of testis RNAs, codes for a predicted one-domain protein similar to the mammalian germinal isoform of angiotensin-converting enzyme. | ỊFEBS Journal Characterization of a membrane-bound angiotensin-converting enzyme isoform in crayfish testis and evidence for its release into the seminal fluid Juraj Simunic Daniel Soyez and Nedia Kamech Equipe Biogenese des Signaux Peptidiques ER3 Universite Pierre et Marie Curie Paris France Keywords angiotensin-converting enzyme crayfish Crustacea spermatogenesis testis Correspondence N. Kamech Equipe Biogenese des Signaux Peptidiques ER3 Universite Pierre et Marie Curie 7 Quai Saint Bernard 75251 Paris Cedex 05 France Fax 33 1 44 27 23 61 Tel 33 1 44 27 22 58 E-mail Received 4 May 2009 revised 18 June 2009 accepted 25 June 2009 doi In the present study an isoform of angiotensin-converting enzyme was characterized from the testis of a decapod crustacean the crayfish Asta-cus leptodactylus. Angiotensin-converting enzyme cDNA obtained by 3 - to 5 RACE of testis RNAs codes for a predicted one-domain protein similar to the mammalian germinal isoform of angiotensin-converting enzyme. All amino acid residues involved in enzyme activity are highly conserved and a potential C-terminus transmembrane anchor may be predicted from the sequence. Comparison of this testicular isoform with angiotensin-converting enzyme from other crustaceans namely Carci-nus maenas Homarus americanus both reconstituted for this study from expressed-sequence tag data and Daphnia pulex suggests that membranebound angiotensin-converting enzyme occurs widely in crustaceans conversely to other invertebrate groups where angiotensin-converting enzyme is predominantly a soluble protein. In situ hybridization and immunohistochemistry performed on testis sections show that angiotensin-converting enzyme mRNA is mainly localized in spermatogonias whereas protein is present in spermatozoids. By contrast in vas deferens immunoreactivity is detected in the seminal fluid rather than in germ cells. Accordingly angiotensin-converting enzyme activity assays .