title: Sperm-egg binding mediated by sperm alpha-L-fucosidase in the ascidian, Halocynthia roretzi.
abstract: Spermatozoa bind to the vitelline coat in the ascidians and many other animals. The binding of sperm in Halocynthia roretzi is mediated by a sperm alpha-L-fucosidase and complementary-L-fucosyl residues of glycoproteins in the vitelline coat. cDNA clones for alpha-L-fucosidase were isolated from growing testis mRNA. It contained a 1398 bp full-length cDNA insert (HrFuc'ase) that encoded the 466 amino acid residues of H. roretzi sperm alpha-L-fucosidase. A putative signal peptide of 21 amino acid residues proceeded the sequence for the mature protein (M.W. 52.4 kDa). The coding sequence for HrFuc'ase showed 47.7% sequence identity to the human liver fucosidase sequence. The polyclonal antibody was prepared against a lacZ-HrFuc'ase fusion protein expressed in E. coli. The antibody crossed to a 54 kDa protein in sperm on western blotting and inhibited fertilization in a dose dependent manner. These data suggest that sperm-egg binding is mediated by the sperm alpha-L-fucosidase, HrFuc'ase in the ascidian, H. roretzi.
authors.affiliation: Center for Life Science and Technology, Graduate School of Science and Technology, Keio University, 3-14-1, Hiyoshi Kouhoku, Yokohama, 223-8522 Japan. mmatsumo@chem.keio.ac.jp
authors.forename: Midori
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Junko
authors.initials: J
authors.lastname: Hirata
authors.forename: Noritaka
authors.initials: N
authors.lastname: Hirohashi
authors.forename: Motonori
authors.initials: M
authors.lastname: Hoshi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002384:Catalysis; D003001:Cloning, Molecular; D007106:Immune Sera / Q000276:immunology; D008297:Male; D008969:Molecular Sequence Data; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013084:Sperm-Ovum Interactions / Q000502:physiology*; D013094:Spermatozoa / Q000201:enzymology*; D014561:Urochordata / Q000201:enzymology* / Q000235:genetics; D005644:alpha-L-Fucosidase / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*
chemical_list: D007106:Immune Sera; D005644:alpha-L-Fucosidase