Melatonin receptors on human granulosa cell membranes.
Putative melatonin binding sites were detected in the membrane fraction of gonadotropin-stimulated human granulosa cells using the melatonin analogue 2-[125I]-iodomelatonin (125I-IML). Saturation studies and Scatchard analysis revealed the presence of a major binding site with a Kd of 99 pM. Guanosine triphosphate shifted the receptor affinity to 380 pM. In competition studies, the rank order of potency of indoles for inhibition of 125I-IML binding at these sites was typical of melatonin receptors: 2-iodomelatonin > melatonin > N-acetylserotonin > 5-methoxytryptamine > serotonin. Culture of cells for 7 days in vitro increased receptor density but not the affinity. These findings strongly suggest that melatonin found in follicular fluid may have a physiological role.
Yie
S M
SM
Department of Obstetrics & Gynecology, McMaster University, Hamilton, Ontario, Canada.
Niles
L P
LP
Younglai
E V
EV
D001665:Binding Sites; D001667:Binding, Competitive; D002462:Cell Membrane / Q000378:metabolism; D005260:Female; D006107:Granulosa Cells / Q000378:metabolism*; D006801:Humans; D007211:Indoles / Q000378:metabolism; D008550:Melatonin / Q000031:analogs & derivatives / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism*; D044094:Receptors, Melatonin
D007211:Indoles; D011956:Receptors, Cell Surface; D044094:Receptors, Melatonin; C044556:2-iodomelatonin; D008550:Melatonin