RFRP-3 efficiently inhibits forskolin-induced production of cAMP with an IC
50
of 0.7 nM.
Scatchard-plot analysis shows that
125
I-labelled hRFRP-3 has a single class of high-affinity binding sites for the membrane fractions of CHO cells expressing rat OT7T022, the K
d
value and the B
max
values are 0.19 nM and 1.3 pM, respectively.RFRP-3 specifically stimulate cells transfected with a new orphan 7TMR, OT7T022, it binds to OT7T022 as a specific ligand with high affinity (K
d
= 0.19 nM).RFRP-3 (10
-8
to 10
-14
M) has no effect on LH and FSH levels alone, but when it combines with GnRH, LH and FSH secretion is significantly reduced by the combination.
