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Biochem Biophys Res Commun 2018 Jan 29;4961:101-104. doi: 10.1016/j.bbrc.2018.01.005.
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Point mutation of a conserved aspartate, D69, in the muscarinic M 2  receptor does not modify voltage-sensitive agonist potency.

Ågren R , Sahlholm K , Nilsson J , Århem P .

The muscarinic M 2 receptor (M 2 R) has been shown to display voltage-sensitive agonist binding, based on G protein-activated inward rectifier potassium channel (GIRK) opening and radioligand binding at different membrane voltages. A conserved aspartate in transmembrane segment (TM) II of M 2 R, D69, has been proposed as the voltage sensor. While a recent paper instead presented evidence of tyrosines in TMs III, VI, and VII acting as voltage sensors, these authors were not able to record GIRK channel activation by a D69N mutant M 2 R. In the present study, we succeeded in recording ACh-induced GIRK channel activation by this mutant at -80 and 0 mV. The acetylcholine EC 50 was about 2.5-fold higher at 0 mV, a potency shift very similar to that observed at wild-type M 2 R, indicating that voltage sensitivity persists at the D69N mutant. Thus, our present observations corroborate the notion that D69 is not responsible for voltage sensitivity of the M 2 R.

PubMed ID: 29305262
Article link: Biochem Biophys Res Commun

Species referenced: Xenopus laevis
Genes referenced: kcnj3 pycard

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