title: Cloning and localisation of an avermectin receptor-related subunit from Haemonchus contortus.
abstract: Ivermectin is believed to exert its anthelminthic effects by binding to glutamate-gated chloride channels (Glu-Cl) and several cDNAs encoding subunits of Glu-Cl have been cloned from Caenorhabditis elegans. We report the cloning of cDNAs encoding a putative Glu-Cl subunit (HG4) from the parasite Haemonchus contortus. The HG4 cDNAs were isolated using RT-PCR and the sequence of the predicted polypeptide has 82% amino-acid identity with the C. elegans Glu-Cl beta subunit. Individual HG4 cDNAs showed up to 4% sequence variation at the nucleotide level, but the vast majority of these polymorphisms were translationally silent. A synthetic peptide corresponding to sequence near the N-terminus of the mature polypeptide was used to raise an antiserum that recognised the N-terminal domain of HG4 expressed in E. coli. Affinity purified antibodies reacted with motor neuron commissures in immuno-localisation studies: these commissures were limited to the anterior portion of the worms, from a region level with the nerve ring to just anterior of the vulva. Some possible nerve cord staining was also observed, but no expression of HG4 on pharyngeal muscle could be detected.
authors.affiliation: Department of Biology and Biochemistry, University of Bath, UK.
authors.forename: N S
authors.initials: NS
authors.lastname: Delany
authors.forename: D L
authors.initials: DL
authors.lastname: Laughton
authors.forename: A J
authors.initials: AJ
authors.lastname: Wolstenholme
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology; D001483:Base Sequence; D015153:Blotting, Western; D018118:Chloride Channels / Q000032:analysis* / Q000187:drug effects / Q000235:genetics*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D005260:Female; D005455:Fluorescent Antibody Technique; D017238:Genes, Helminth; D006189:Haemonchus / Q000737:chemistry / Q000235:genetics*; D015801:Helminth Proteins / Q000235:genetics*; D007559:Ivermectin / Q000031:analogs & derivatives / Q000494:pharmacology; D008969:Molecular Sequence Data; D009046:Motor Neurons / Q000737:chemistry; D017470:Receptors, Glutamate / Q000032:analysis* / Q000187:drug effects / Q000235:genetics*; D016415:Sequence Alignment; D012756:Sheep / Q000469:parasitology
chemical_list: D000871:Anthelmintics; D018118:Chloride Channels; D018076:DNA, Complementary; C117860:HG4 protein, Haemonchus contortus; D015801:Helminth Proteins; D017470:Receptors, Glutamate; D007559:Ivermectin; C019264:avermectin