Pakistan Journal of Biological Sciences1028-88801812-5735Asian Network for Scientific Information10.3923/pjbs.2012.1133.1138Tetrahymena thermophila by Fluorescent Ligands]]>Ud-DaulaAsad PfisterGerd SchrammKarl-Werner 1220121523Two 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.]]>Amenta, F., E. Bronzetti, L. Felici, A. Ricci and S.K. Tayebati,199919151159Ariano, M.A., F.J. Jr Monsma, A.C. Barton, H.C. Kang, R.P. Haugland and D.R. Sibley,19898685708574Creese, I., D.R. Sibley, M.W. Hamblin and S.E. Leff,198364371Dohlman, H.G., J. Thorner, M.G. Caron and R.J. Lefkowitz,199160653688Enjalbert, A., F. Sladczed, G. Guillon, P. Bertrand and C. Shu et al.,198626140714075Furukawa, T. and H. Morishita,1997328229234Iorio, L.C., A. Barnett, F.H. Leitz, V.P. Houser and C.A. Korduba,1983226462468Kaiser, C., P.A. Dandridge, E. Garvey, R.A. Hahn and H.M. Sarau et al.,198225697703Lacey, M.G., N.B. Mercuri and R.A. North,1987392397416Monsma, F.J., A.C. Barton, H.C. Kang, D.L. Brassard, R.P. Haugland and D.R. Sibley,19895216411644Ng, G.Y., B. Mouillac, S.R. George, M. Caron, M. Dennis, M. Bouvier and B.F. O'Dowd,1994267719O'Dowd, B.F.,199360804816Ongini, E., M.G. Caporali and M. Massotti,19853723272333Prou, D., W.J. Gu, L.S. Crom, J.D. Vincent, J. Salamero and P. Vernier,200111435173527Sun, W., N. Ginovart, F. Ko, P. Seeman and S. Kapur,2003In vivo evidence for dopamine mediated internalization of D2-receptors after amphetamine: Differential findings with [3H] raclopride versus [3H]spiperone.]]>63456462Ud-Daula, A., G. Pfister and K.W. Schramm,2008Tetrahymena pyriformis.]]>4316101617Vickery, R.G. and M. von Zastrow,19991443143Zhu, Z.T., Y. Fu, G.Y. Hu and G.Z. Jin,200052123130