The M2 muscarinic G-protein-coupled receptor is voltage-sensitive

Yair Ben-Chaim, Oded Tour, Nathan Dascal, Itzchak Parnas, Hanna Parnas

نتاج البحث: نشر في مجلةمقالةمراجعة النظراء


G-protein coupled receptors are not considered to exhibit voltage sensitivity. Here, using Xenopus oocytes, we show that the M2 muscarinic receptor (m2R) is voltage-sensitive. The m2R-mediated potassium channel (GIRK) currents were used to assay the activity of m2R. We found that the apparent affinity of m2R toward acetylcholine (ACh) was reduced upon depolarization. Binding experiments of [3H]ACh to individual oocytes expressing m2R confirmed the electrophysiological findings. When the GIRK channels were activated either by overexpression of Gβγ subunits or by injection of GTPγS, the ratio between the currents measured at -60 mV and +40 mV was the same as for the basal activity of the GIRK channel. Thus, the steps downstream to agonist activation of m2R are not voltage-sensitive. We further found that, in contrast to m2R, the apparent affinity of m1R was increased upon depolarization. We also found that the voltage sensitivity of binding of [3H]ACh to oocytes expressing m2R was greatly diminished following pretreatment with pertussis toxin. The cumulative results suggest that m2R is, by itself, voltage-sensitive. Furthermore, the voltage sensitivity does not reside in the ACh binding site, rather, it most likely resides in the receptor region that couples to the G-protein.

اللغة الأصليةالإنجليزيّة
الصفحات (من إلى)22482-22491
عدد الصفحات10
دوريةJournal of Biological Chemistry
مستوى الصوت278
رقم الإصدار25
المعرِّفات الرقمية للأشياء
حالة النشرنُشِر - 20 يونيو 2003
منشور خارجيًانعم


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