title: Binding of Bacillus sphaericus binary toxin to a specific receptor on midgut brush-border membranes from mosquito larvae.
abstract: The presence of specific receptors for Bacillus sphaericus binary toxin on brush-border membrane fractions (BBMF) from Culex pipiens larvae midgut cells was demonstrated by an in vitro binding assay. Both activated and radiolabelled polypeptides from the 51-kDa and 42-kDa binary toxin of B. sphaericus 1593 specifically bound to BBMF. Direct binding and homologous competition experiments indicated a single class of B. sphaericus toxin receptors, with a dissociation constant (Kd) of approximately 20 nM and a maximum binding capacity (Bmax) of approximately 7 pmol/mg BBMF protein. The sugars GalNAc, GlcNAc and N-acetyl neuraminic acid had no detectable inhibitory effect on toxin binding to C. pipiens BBMF. Binding experiments with the non-susceptible mosquito species Aedes aegypti failed to detect significant binding of B. sphaericus binary toxin to A. aegypti BBMF.
authors.affiliation: Bactéries Entomopathogènes, Institut Pasteur, Paris, France.
authors.forename: C
authors.initials: C
authors.lastname: Nielsen-Leroux
authors.forename: J F
authors.initials: JF
authors.lastname: Charles
mesh_terms: D000116:Acetylgalactosamine / Q000494:pharmacology; D000117:Acetylglucosamine / Q000494:pharmacology; D000330:Aedes / Q000378:metabolism; D000818:Animals; D001427:Bacterial Toxins / Q000378:metabolism*; D001667:Binding, Competitive; D003465:Culex / Q000378:metabolism*; D007814:Larva / Q000378:metabolism / Q000648:ultrastructure; D008871:Microvilli / Q000187:drug effects / Q000378:metabolism; D019158:N-Acetylneuraminic Acid; D011955:Receptors, Drug / Q000378:metabolism*; D012794:Sialic Acids / Q000494:pharmacology
chemical_list: D001427:Bacterial Toxins; D011955:Receptors, Drug; D012794:Sialic Acids; C046134:binB protein, Bacillus sphaericus; D019158:N-Acetylneuraminic Acid; D000116:Acetylgalactosamine; D000117:Acetylglucosamine