title: L-(3H) glutamate binding to a membrane preparation from the optic lobe of the giant freshwater prawn Macrobrachium rosenbergii de Man.
abstract: Membrane preparation from the optic lobe of the giant freshwater prawn, Macrobrachium rosenbergii de Man, was examined for the presence of specific L-(3H) glutamate binding. The optic lobes were isolated from live animals. The tissue was homogenized and the membrane fraction isolated by differential centrifugation. The membrane suspension was incubated with 10-1,000 nM of L-(3H) glutamate at 37 degrees C for 60 min. Nonspecific binding was determined by incubating the mixture with 100 microM L-glutamate. L-(3H) glutamate specifically bound to the membrane fraction with a dissociation equilibrium constant (Kd) of 205 nM and maximum number of binding sites (Bmax) of 2.04 n mol/mg protein. By using LIGAND computerized program, the saturation isotherm binding pattern indicates a single type of binding. To determine the type of glutamate receptors, competitive inhibition and IC50 of several glutamate agonists and antagonists were determined. The study reveals a metabotropic type of binding site.
authors.affiliation: Department of Anatomy, Faculty of Science, Mahidol University, Bangkok, Thailand.
authors.forename: P
authors.initials: P
authors.lastname: Pratumtan
authors.forename: P
authors.initials: P
authors.lastname: Govitrapong
authors.forename: B
authors.initials: B
authors.lastname: Withyachumnarnkul
authors.forename: B
authors.initials: B
authors.lastname: Poolsanguan
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D002118:Calcium / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D018691:Excitatory Amino Acid Antagonists; D005971:Glutamates / Q000378:metabolism*; D018698:Glutamic Acid; D008565:Membrane Proteins / Q000378:metabolism; D009899:Optic Lobe, Nonmammalian / Q000187:drug effects / Q000378:metabolism*; D033541:Palaemonidae / Q000378:metabolism*
chemical_list: D018691:Excitatory Amino Acid Antagonists; D005971:Glutamates; D008565:Membrane Proteins; D018698:Glutamic Acid; D002118:Calcium