Binding of \g=b\-galactosidasefrom rat epididymal fluid to the sperm surface by high-affinity sites different from phosphomannosyl receptors

MIGUEL A. SOSA; BARBIERI A; BERTINI F

JOURNAL OF REPRODUCTION AND FERTILITY

Journals of Reproduction and Fertility & Ltd

Año: 1991 vol. 93 p. 279 - 285

0022-4251

Summary. \g=b\-Galactosidase,known to be secreted by epithelial cells lining the ratepididymal duct, binds to the surface of spermatozoa from the caudal region withhigh affinity and in a saturable form. The binding was not inhibited by mannose-6\x=req-\phosphate, but was inhibited by fructose phosphate derivatives, a peculiarity previouslydemonstrated for the membranes of epididymal tissue. Fructose phosphate derivativesreleased 55% of \g=b\-galactosidaseactivity from the spermatozoa. These results suggestthat in the epididymis there is a special transport system for hydrolases, which could beinvolved in the secretion of enzymes destined for spermatozoa. This transport wouldrequire receptors that recognize sugar ligands other than mannose-6-phosphate. Thesereceptors were present in the epididymal tissue and on the sperm surface.