title: Identification of dopamine receptor in Tetrahymena thermophila by fluorescent ligands.
abstract: Two types dopamine receptor present in the cell membrane of vertebrates. But in this study D1 receptor was identified in the invertebrate ciliates protozoan, Tetrahymena thermophila by use of fluorescent ligands. D1 specific agonist SKF-38393 binds specifically to Tetrahymena. The specific binding of SKF-38393 was encountered by equimolar addition of D1 antagonist thus showed no binding of ligands. In addition, it was also proved that the D1 specific agonist did not cross bind with the D2 type receptor due to the equimolar addition of D2 selective antagonist spiperone. Interestingly this study also showed that the dopamine receptor present in the endoplasmic reticulum and endosomes of Tetrahymena as well as cell membrane which was revealed by laser scanning microscope. Therefore, this evidence supports the existence of a D1 receptor in the ciliate protozoan.
authors.affiliation: Helmholtz Zentrum Miinchen, German Research Center for Environmental Health, Institute of Ecological Chemistry, Ingolstiidter Landstrasse 1, D-85764 Neuherberg, Germany.
authors.forename: Asad
authors.initials: A
authors.lastname: Ud-Daula
authors.forename: Gerd
authors.initials: G
authors.lastname: Pfister
authors.forename: Karl-Werner
authors.initials: KW
authors.lastname: Schramm
mesh_terms: D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000031:analogs & derivatives / Q000378:metabolism; D001552:Benzazepines / Q000378:metabolism; D018491:Dopamine Agonists / Q000378:metabolism; D018492:Dopamine Antagonists / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism; D008024:Ligands; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D015800:Protozoan Proteins / Q000378:metabolism*; D017447:Receptors, Dopamine D1 / Q000378:metabolism*; D012235:Rhodamines / Q000378:metabolism; D013134:Spiperone / Q000031:analogs & derivatives / Q000378:metabolism; D016808:Tetrahymena thermophila / Q000378:metabolism*
chemical_list: D001552:Benzazepines; D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D005456:Fluorescent Dyes; D008024:Ligands; D015800:Protozoan Proteins; D017447:Receptors, Dopamine D1; D012235:Rhodamines; C534628:SCH 23390; D013134:Spiperone; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine