Identification of a Crucial Amino Acid in the Helix Position 6.51 of Human Tachykinin Neurokinin 1 and 3 Receptors Contributing to the Insurmountable Mode of Antagonism by Dual NK1/NK3 Antagonists
摘要:
The neurokinins are neuropeptides that elicit their effect through three GPCRs called NK1, NK2, and NK3. Compounds 5 and 6 are dual hNK(1) (K-1 of 0.7 and 0.3 nM) and hNK(3) (K-1 of 2.9 and 1.7 nM) antagonists. Both compounds exhibit an insurmountable mode of antagonism at hNK(1), whereas at hNK(3), they differ in that 5 is an insurmountable but 6 a surmountable antagonist. Using homology modeling and site-directed mutagenesis, hNK(1)-Phe264 and hNK(3)-Tyr315 were found to be the molecular determinants of hNK(1) and hNK(3) antagonism by 5 and 6. In [H-3]IP studies, the mutation hNK(1)-F264Y converted the mode of action of 5 from insurmountable to partial insurmountable antagonism while it had no effect on that of 6. Conversely, the mutation hNK(3)-Y315F enhanced the insurmountable behavior of 5 and converted 6's surmountable to an insurmountable antagonism. This finding was further confirmed by characterizing additional derivatives of 5 and 6, most notably with a hybrid structure.
Identification of a Crucial Amino Acid in the Helix Position 6.51 of Human Tachykinin Neurokinin 1 and 3 Receptors Contributing to the Insurmountable Mode of Antagonism by Dual NK1/NK3 Antagonists
摘要:
The neurokinins are neuropeptides that elicit their effect through three GPCRs called NK1, NK2, and NK3. Compounds 5 and 6 are dual hNK(1) (K-1 of 0.7 and 0.3 nM) and hNK(3) (K-1 of 2.9 and 1.7 nM) antagonists. Both compounds exhibit an insurmountable mode of antagonism at hNK(1), whereas at hNK(3), they differ in that 5 is an insurmountable but 6 a surmountable antagonist. Using homology modeling and site-directed mutagenesis, hNK(1)-Phe264 and hNK(3)-Tyr315 were found to be the molecular determinants of hNK(1) and hNK(3) antagonism by 5 and 6. In [H-3]IP studies, the mutation hNK(1)-F264Y converted the mode of action of 5 from insurmountable to partial insurmountable antagonism while it had no effect on that of 6. Conversely, the mutation hNK(3)-Y315F enhanced the insurmountable behavior of 5 and converted 6's surmountable to an insurmountable antagonism. This finding was further confirmed by characterizing additional derivatives of 5 and 6, most notably with a hybrid structure.