Looking for an experimental model for functional studies on caltrin-like proteins from human seminal plasma

ANAHí FRANCHI; CONRADO AVENDAñO; CARLOS E. CORONEL

Buenos Aires, Argentina

Workshop; V Jornadas Multidisciplinarias de la Sociedad Argentina de Biología; 2004

Sociedad Argentina de Biología

Caltrin (calcium transport inhibitor) inhibits Ca2+ extracellular uptake and prevents the spontaneous acrosome reaction in epipidymal spermatozoa from guinea pigs, rats and mice. Using anti-guinea pig caltrin antibodies, two immunoreactive proteins of 15 and 34 kDa were detected by SDS-PAGE and Western blotting in human seminal plasma. They were purified, sequenced and designed as p15 and p34 respectively. P15 is a glycoprotein whose sequence has homology with that of â-microseminoprotein (â-MSP), while p34 sequence shows homology with that of the prostate specific antigen (PSA). By indirect immunofluorescence with anti-p15 and anti-p34 antibodies, p15 was localized on the anterior region of the head and the neck, while p34 on the post-acrosomal area of ejaculated spermatozoa. Data suggested that both proteins bind to the cell during ejaculation as it was observed in the mouse. Because of the difficulty of to obtain human epididymal sperm to confirm this hypothesis and to study in detail the functional properties of p15 and p34 proteins, the possibility to use the guinea pig as an experimental model has been evaluated. The ability of p15 to interact with epididymal guinea pig spermatozoa was investigated. As it was previously reported for guinea pig caltrin I, p15 was able to bind to the acrosomal area and to reduce the percentage of spontaneous acrosome reaction in guinea pig sperm. According to these results, guinea pig spermatozoa will allow as to use them as an experimental model for studying the functional properties of human seminal plasma proteins.