title: Interactions between ovine cathepsin L, cystatin C and alpha 2-macroglobulin. Potential role in the genital tract.
abstract: The specific inhibitor of cysteine proteinases, cystatin C, was purified from ram rete testis fluid and the conditioned medium of Sertoli cells. This molecule associated with sheep liver cathepsin L at one of the fastest rates ever described for a proteinase/inhibitor interaction (1.75 +/- 0.20 x 10(8) M-1.s-1). But the association rate constant for the interaction of cathepsin L with alpha 2-macroglobulin, a non-specific inhibitor of proteinases, was also extremely high (8.8 +/- 0.75 x 10(6) M-1.s-1). Cathepsin L complexed with alpha 2-macroglobulin was protected from inhibition by type 2 and type 3 cystatins. The data indicate that cystatin C is the most potent inhibitor of cathepsin L in mammalian male genital tract fluids, whereas alpha 2-macroglobulin may act as a terminal acceptor of this enzyme. These inhibitors could therefore inhibit the activated form of procathepsin L which may appear during the complex process of spermatozoa production and maturation in the testis and epididymis.
authors.affiliation: Laboratoire d'Enzymologie et Chimie des Protéines, EP CNRS 117, Université François Rabelais, Tours, France.
authors.forename: S
authors.initials: S
authors.lastname: Peloille
authors.forename: A
authors.initials: A
authors.lastname: Esnard
authors.forename: J L
authors.initials: JL
authors.lastname: Dacheux
authors.forename: F
authors.initials: F
authors.lastname: Guillou
authors.forename: F
authors.initials: F
authors.lastname: Gauthier
authors.forename: F
authors.initials: F
authors.lastname: Esnard
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D056668:Cathepsin L; D002403:Cathepsins / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology; D055316:Cystatin C; D015891:Cystatins / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D004357:Drug Synergism; D010450:Endopeptidases; D008297:Male; D008969:Molecular Sequence Data; D012152:Rete Testis / Q000187:drug effects / Q000378:metabolism*; D012708:Sertoli Cells / Q000187:drug effects / Q000378:metabolism; D012756:Sheep; D000511:alpha-Macroglobulins / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D055316:Cystatin C; D015891:Cystatins; D000511:alpha-Macroglobulins; D002403:Cathepsins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; D056668:Cathepsin L