title: Target size analysis of an avermectin binding site from Drosophila melanogaster.
abstract: A high-affinity avermectin binding site from Drosophila melanogaster head membranes was subjected to target size analysis by radiation inactivation in order to determine the functional unit size. Using the [3H]ivermectin binding assay to assess ligand binding activity, the target size was determined to be 44.3 +/- 3.9 kDa. This result suggests that the size of the functional unit required for high-affinity ligand binding is a monomer. The membrane-associated acetylcholinesterase present in the Drosophila head membranes was also analyzed by radiation inactivation and served as a control. By monitoring enzymatic activity, the functional unit size of the Drosophila acetylcholinesterase was determined to be 70 +/- 9.7 kDa. This corresponds to the molecular weight of a dimer composed of a 55 kDa subunit and a 16-18 kDa subunit.
authors.affiliation: Department of Cell and Biochemical Physiology, Merck Research Laboratories, Rahway, NJ 07065, USA.
authors.forename: A
authors.initials: A
authors.lastname: Pomes
authors.forename: E
authors.initials: E
authors.lastname: Kempner
authors.forename: S
authors.initials: S
authors.lastname: Rohrer
mesh_terms: D000110:Acetylcholinesterase / Q000737:chemistry; D000818:Animals; D001665:Binding Sites; D018118:Chloride Channels / Q000378:metabolism; D004331:Drosophila melanogaster / Q000737:chemistry* / Q000378:metabolism; D007306:Insecticides / Q000737:chemistry*; D007559:Ivermectin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism
chemical_list: D018118:Chloride Channels; D007306:Insecticides; D007559:Ivermectin; C019264:avermectin; D000110:Acetylcholinesterase