Interaction of [3H]nomegestrol acetate with cytosolic progesterone receptors from the rat uterus.
The binding characteristics of the progestin 17 alpha-acetoxy-6-methyl-19-[3H]norpregna-4,6-diene-3,20-dione, nomegestrol acetate ([3H]NOM-Ac) to progesterone receptors (PgRs) of uterus were determined in the rat. Scatchard plot analysis of the equilibrium binding data showed that [3H]NOM-Ac binds to uterine PgR with a Kd of 5.44 +/- 1.27 nM and a Bmax of 1.51 +/- 0.11 pmol/mg protein. Analysis of dissociation kinetics showed that [3H]NOM-Ac dissociates slowly from the PgR, k - 1 = 4.9 +/- 0.5 10(-5) s-1. Competition experiments against [3H]NOM-Ac showed the specificity of the binding with a sequence in relative affinity as follows: ORG 2058 greater than P greater than NOM-Ac greater than medroxyprogesterone acetate greater than megestrol acetate greater than cyproterone acetone greater than NOM.
Duc
I
I
Laboratoire Theramex, Principauté de Monaco, Service de Biologie Cellulaire.
Botella
J
J
Delansorne
R
R
Paris
J
J
D000818:Animals; D001667:Binding, Competitive; D003600:Cytosol / Q000378:metabolism*; D005260:Female; D007700:Kinetics; D008535:Megestrol; D009649:Norpregnadienes / Q000378:metabolism*; D045167:Progesterone Congeners / Q000378:metabolism*; D051381:Rats; D011980:Receptors, Progesterone / Q000378:metabolism*; D014599:Uterus / Q000378:metabolism*
D009649:Norpregnadienes; D045167:Progesterone Congeners; D011980:Receptors, Progesterone; C038501:nomegestrol acetate; D008535:Megestrol