N-bromoacetyl 5-methoxytryptamine: an irreversible melatonin ligand?
The effects of N-bromoacetyl 5-methoxytryptamine (BraMT) and some related bromoacyl melatonin and tryptamine derivatives on 2-[125I]iodomelatonin (2-[125I]aMT) binding in chicken brain membranes were examined. All analogues displaced specific binding to chicken brain membranes in a concentration-dependent manner. Preincubation of chicken brain membranes with BraMT (10(-8)M) did not significantly alter either 2-[125I]aMT binding site affinity (Kd) or density (Bmax). SDS polyacrylamide gel electrophoresis of chicken brain membrane proteins preincubated with 2-[125I]BraMT indicated that numerous proteins were labelled. The incorporation of radiolabel into these proteins was not blocked by melatonin, 2-iodomelatonin or N-(1,4 dinitrophenyl)-5-methoxytryptamine (ML-23), but was reduced by BraMT. In contrast to previous reports on hamster and rat brain membranes, the present results provide no evidence that BraMT or 2-[125I]BraMT affinity labels specific melatonin binding proteins in chicken brain.
Biomedical Sciences Division, King's College London, U.K.
N W
NW
Chong
J E
JE
Evans
D
D
Sugden
D008735:5-Methoxytryptamine / Q000031:analogs & derivatives* / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002645:Chickens; D007457:Iodine Radioisotopes; D007700:Kinetics; D008550:Melatonin / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology; D044094:Receptors, Melatonin; D017981:Receptors, Neurotransmitter / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014363:Tryptamines / Q000378:metabolism* / Q000494:pharmacology
D007457:Iodine Radioisotopes; D044094:Receptors, Melatonin; D017981:Receptors, Neurotransmitter; D014363:Tryptamines; C082028:N-bromoacetyl-5-methoxytryptamine; D008735:5-Methoxytryptamine; C030820:tryptamine; D008550:Melatonin