title: Purification, structure, and characterization of caltrin proteins from seminal vesicle of the rat and mouse.
abstract: Caltrins, small basic proteins that inhibit calcium uptake by epididymal spermatozoa, have been purified from seminal vesicle content of the mouse and rat. Mouse caltrin (M(r) 8,476) contains 75 amino acid residues, 14 basic, 5 acidic, and 7 cysteines while rat caltrin (M(r) 6,217) has 56 residues, 10 basic, 5 acidic, and 6 cysteines; their pI values are 10.2 and 9.3, respectively. The proteins did not react with Ellman's reagent unless the cystine residues were previously reduced. The primary structures were determined by sequencing fragments generated by trypsin, clostripain, and endoproteinase Lys-C digestion. The sequences were ordered to give the total structural formula. The two molecules have no sequence similarity and are different from those of the bull and guinea pig previously reported. Only rat caltrin has a sequence of 13 residues nearly identical to that in guinea pig caltrin I. Both rat and mouse caltrin react with antibodies against bovine and guinea pig caltrins. Reduction and alkylation of cysteine residues suppressed the immunologic response of mouse caltrin; however, modified rat caltrin retained partially its immunoreactivity with the antiserum against guinea pig caltrin I. The same treatment abolished the calcium transport inhibitory activity of mouse caltrin and greatly reduced that of rat caltrin. It is likely that rat and mouse caltrins have the same physiological function as proposed for bovine caltrin; namely, to regulate the development of the Ca(2+)-dependent processes that "capacitate" sperm for fertilization.
authors.affiliation: Cátedra de Química Biológica, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Argentina.
authors.forename: C E
authors.initials: CE
authors.lastname: Coronel
authors.forename: D E
authors.initials: DE
authors.lastname: Winnica
authors.forename: M L
authors.initials: ML
authors.lastname: Novella
authors.forename: H A
authors.initials: HA
authors.lastname: Lardy
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D002852:Chromatography, Ion Exchange; D003545:Cysteine / Q000032:analysis; D004591:Electrophoresis, Polyacrylamide Gel; D007525:Isoelectric Focusing; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000302:isolation & purification; D029584:Prostatic Secretory Proteins; D011506:Proteins / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D051381:Rats; D029589:Seminal Plasma Proteins; D012669:Seminal Vesicles / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013075:Sperm Capacitation; D013094:Spermatozoa / Q000378:metabolism
chemical_list: D010446:Peptide Fragments; D029584:Prostatic Secretory Proteins; D011506:Proteins; D029589:Seminal Plasma Proteins; C043076:beta-microseminoprotein; D003545:Cysteine; D002118:Calcium