title: Binding of beta-galactosidase from rat epididymal fluid to the sperm surface by high-affinity sites different from phosphomannosyl receptors.
abstract: beta-Galactosidase, known to be secreted by epithelial cells lining the rat epididymal duct, binds to the surface of spermatozoa from the caudal region with high affinity and in a saturable form. The binding was not inhibited by mannose-6-phosphate, but was inhibited by fructose phosphate derivatives, a peculiarity previously demonstrated for the membranes of epididymal tissue. Fructose phosphate derivatives released 55% of beta-galactosidase activity from the spermatozoa. These results suggest that in the epididymis there is a special transport system for hydrolases, which could be involved in the secretion of enzymes destined for spermatozoa. This transport would require receptors that recognize sugar ligands other than mannose-6-phosphate. These receptors were present in the epididymal tissue and on the sperm surface.
authors.affiliation: Instituto de Histología y Embriología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo-C.C. 56, Mendoza, Argentina.
authors.forename: M A
authors.initials: MA
authors.lastname: Sosa
authors.forename: M A
authors.initials: MA
authors.lastname: Barbieri
authors.forename: F
authors.initials: F
authors.lastname: Bertini
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism; D004822:Epididymis / Q000201:enzymology*; D005636:Fructosephosphates / Q000378:metabolism; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013094:Spermatozoa / Q000378:metabolism*; D001616:beta-Galactosidase / Q000378:metabolism*
chemical_list: D005636:Fructosephosphates; C027618:fructose-6-phosphate; D001616:beta-Galactosidase