title: Differential effects of guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) on the 2-[125I]iodomelatonin binding sites in the chicken bursa of Fabricius and spleen.
abstract: Effects of 10 and 50 mumol/l guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) on 2-[125I]iodomelatonin binding in the chicken bursa of Fabricius and spleen were tested. In the chicken bursa of Fabricius, GTP gamma S increased the Kd of 2-[125I]iodomelatonin binding sites without affecting the Bmax value. In contrast, GTP gamma S caused both an increase in Kd and a reduction in Bmax of 2-[125I]iodomelatonin binding sites in the chicken spleen. Our results suggest the existence of subtypes of melatonin receptors with different receptor-G protein-effector complexes in the avian primary and secondary lymphoid systems.
authors.affiliation: Department of Physiology, University of Hong Kong.
authors.forename: A M
authors.initials: AM
authors.lastname: Poon
authors.forename: S F
authors.initials: SF
authors.lastname: Pang
mesh_terms: D000818:Animals; D002060:Bursa of Fabricius / Q000187:drug effects / Q000378:metabolism*; D002645:Chickens; D015536:Down-Regulation / Q000187:drug effects; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology*; D006160:Guanosine Triphosphate / Q000494:pharmacology; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes; D007700:Kinetics; D008550:Melatonin / Q000378:metabolism; D008566:Membranes / Q000187:drug effects / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism*; D044094:Receptors, Melatonin; D013154:Spleen / Q000187:drug effects / Q000378:metabolism*
chemical_list: D007457:Iodine Radioisotopes; D011956:Receptors, Cell Surface; D044094:Receptors, Melatonin; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D008550:Melatonin