title: alpha-Mannosidase from rat epididymal fluid is a ligand for phosphomannosyl receptors on the sperm surface.
abstract: This study demonstrates that alpha-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 alpha-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 alpha-mannosidase. These findings suggest a new role for extracellular transport mediated by the mannose-6-phosphate receptor.
authors.affiliation: Instituto de Histología y Embriología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina.
authors.forename: S A
authors.initials: SA
authors.lastname: Belmonte
authors.forename: A
authors.initials: A
authors.lastname: Challa
authors.forename: L S
authors.initials: LS
authors.lastname: Gutierrez
authors.forename: F
authors.initials: F
authors.lastname: Bertini
authors.forename: M A
authors.initials: MA
authors.lastname: Sosa
mesh_terms: D000818:Animals; D001826:Body Fluids / Q000201:enzymology; D004822:Epididymis / Q000201:enzymology; D006863:Hydrogen-Ion Concentration; D008024:Ligands; D008297:Male; D008361:Mannosidases / Q000378:metabolism*; D051381:Rats; D017527:Receptor, IGF Type 2; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D013094:Spermatozoa / Q000378:metabolism*; D043323:alpha-Mannosidase
chemical_list: D008024:Ligands; D017527:Receptor, IGF Type 2; D018160:Receptors, Cytoplasmic and Nuclear; C034304:cation-dependent mannose-6-phosphate receptor; D008361:Mannosidases; D043323:alpha-Mannosidase