α-Mannosidase from rat epididymal fluid is a ligand for phosphomannosyl receptors on the sperm surface

• Published in: International journal of andrology Vol. 21; no. 5; pp. 277 - 282
• Main Authors: BELMONTE, S. A, CHALLA, A, GUTIERREZ, L. S, BERTINI, F, SOSA, M. A
• Format: Journal Article
• Language: English
• Published: Oxford UK Blackwell Science Ltd 01.10.1998; Blackwell
• Subjects: acid hydrolases; alpha-Mannosidase; Animals; Biological and medical sciences; Body Fluids - enzymology; epididymis; Epididymis - enzymology; Fundamental and applied biological sciences. Psychology; Hydrogen-Ion Concentration; Ligands; Male; Mammalian male genital system; Mannosidases - metabolism; Morphology. Physiology; phosphomannosyl receptors; Rats; Receptor, IGF Type 2; Receptors, Cytoplasmic and Nuclear - metabolism; spermatozoa; Spermatozoa - metabolism; Vertebrates: reproduction; α-mannosidase; Art; Spermatozoa; Enzyme; Ligand; Male; Male genital duct; Epididymal fluid; Germinal cell; Male genital system; Cell surface; Epididymis; Binding capacity; Glycosidases; α-Mannosidase; Hydrolases; Carbohydrate; Carbohydrate chain; O-Glycosidases; Biological receptor
• ISSN: 0105-6263; 1365-2605
• DOI: 10.1046/j.1365-2605.1998.00124.x

This study demonstrates that α‐mannosidase from rat epididymal fluid is a ligand for phosphomannosyl receptors on the sperm surface. This enzyme was bound to intact epididymal spermatozoa with high affinity and in saturable form, and the binding was inhibited by mannose‐6‐phosphate but not by phosphorylated derivatives of fructose. Treatment of the enzyme with sodium periodate inhibited the binding of α‐mannosidase, confirming that a carbohydrate residue is involved in the interaction with spermatozoa. Evidence is also presented that the cation‐independent phosphomannosyl receptors are responsible for the interaction with α‐mannosidase. These findings suggest a new role for extracellular transport mediated by the mannose‐6‐phosphate receptor.