Analysis of [[beta].sub.2]AR-[G.sub.s] and [[beta].sub.2]AR-[G.sub.i] complex formation by NMR spectroscopy.

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Date: Sept. 15, 2020
Publisher: National Academy of Sciences
Document Type: Report
Length: 6,196 words
Lexile Measure: 1440L

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Abstract :

The [[beta].sub.2]-adrenergic receptor ([[beta].sub.2]AR) is a prototypical G protein-coupled receptor (GPCR) that preferentially couples to the stimulatory G protein [G.sub.s] and stimulates cAMP formation. Functional studies have shown that the [[beta].sub.2]AR also couples to inhibitory G protein [G.sub.i], activation of which inhibits cAMP formation [R. P. Xiao, Sci. STKE 2001, re15 (2001)]. A crystal structure of the [[beta].sub.2]AR-[G.sub.s] complex revealed the interaction interface of [[beta].sub.2]AR-[G.sub.s] and structural changes upon complex formation [S. G. Rasmussen et al., Nature 477, 549-555 (2011)], yet, the dynamic process of the [[beta].sub.2]AR signaling through [G.sub.s] and its preferential coupling to [G.sub.s] over [G.sub.i] is still not fully understood. Here, we utilize solution nuclear magnetic resonance (NMR) spectroscopy and supporting molecular dynamics (MD) simulations to monitor the conformational changes in the G protein coupling interface of the [[beta].sub.2]AR in response to the full agonist BI-167107 and [G.sub.s] and [G.sub.i1]. These results show that BI-167107 stabilizes conformational changes in four transmembrane segments (TM4, TM5, TM6, and TM7) prior to coupling to a G protein, and that the agonist-bound receptor conformation is different from the G protein coupled state. While most of the conformational changes observed in the [[beta].sub.2]AR are qualitatively the same for [G.sub.s] and [G.sub.i1], we detected distinct differences between the [[beta].sub.2]AR-[G.sub.s] and the [[beta].sub.2]AR-[G.sub.i1] complex in intracellular loop 2 (ICL2). Interactions with ICL2 are essential for activation of [G.sub.s]. These differences between the [[beta].sub.2]AR-[G.sub.s] and [[beta].sub.2]AR-[G.sub.i1] complexes in ICL2 may be key determinants for G protein coupling selectivity. GPCR | [[beta].sub.2]-adrenergic receptor | NMR spectroscopy | G protein coupling specificity

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Gale Document Number: GALE|A637713383