a-Mannosidase from rat epididymal ¯uid is a ligand for phosphomannosyl receptors on the sperm surface

BELMONTE SA; CHALLA A; GUTIERREZ LS; BERTINI F; SOSA MA

INTERNATIONAL JOURNAL OF ANDROLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 1998 vol. 21 p. 277 - 282

0105-6263

SummaryThis study demonstrates that a-mannosidase from rat epididymal ¯uid is a ligand forphosphomannosyl receptors on the sperm surface. This enzyme was bound to intactepididymal spermatozoa with high af®nity and in saturable form, and the binding wasinhibited by mannose-6-phosphate but not by phosphorylated derivatives of fructose.Treatment of the enzyme with sodium periodate inhibited the binding of a-mannosidase,con®rming that a carbohydrate residue is involved in the interaction withspermatozoa. Evidence is also presented that the cation-independent phosphomannosylreceptors are responsible for the interaction with a-mannosidase. These ®ndings suggesta new role for extracellular transport mediated by the mannose-6-phosphate receptor.