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The Presence of a Glycosyl Phosphatidylinositol‐Anchored α‐Mannosidase in Boar Sperm

2000; Wiley; Volume: 49; Issue: 6 Linguagem: Inglês

10.1080/15216540050167016

1521-6551

Masako Kuno, Naoto Yonezawa, S. Amari, Masayuki Hayashi, Yuichiro Ono, László Kiss, Kuniharu Sonohara, Minoru Nakano,

Lysosomal Storage Disorders Research

alpha-Mannosidase and beta-galactosidase were released from boar sperm into the medium by treatment with calcium ionophore A23187 or by 0.2% Brij-35/2% acetic acid. About half as much alpha-mannosidase activity as that in the acid extract was recovered by digestion with phosphatidylinositol-specific phospholipase C (PI-PLC), whereas the liberation rate of beta-galactosidase treated with PI-PLC was low. These results suggest that some alpha-mannosidase is anchored in the plasma membrane of the acrosomal region by attachment to the lipid phosphatidylinositol and that beta-galactosidase is localized mainly in the acrosome or integrated in the plasma membrane by a spanning stretch of hydrophobic peptides. beta-Galactosidase, which is present as an oligomers in the acid extract of sperm, dissociated into monomers under weakly alkaline conditions; under acidic conditions, the monomers associated again. No pH-sensitive association-dissociation of alpha-mannosidase was observed.