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Title: Impact of purification conditions and history on A 2A adenosine receptor activity: The role of CHAPS and lipids

The adenosine A 2A receptor (A 2AR) is a much-studied class A G protein-coupled receptor (GPCR). For biophysical studies, A 2AR is commonly purified in a detergent mixture of dodecylmaltoside (DDM), 3-(3-cholamidopropyl) dimethylammoniopropane sulfonate (CHAPS), and cholesteryl hemisuccinate (CHS). Here we studied the effects of CHAPS on the ligand binding activity and stability of wild type, full-length human A 2AR. We also tested the cholesterol requirement for maintaining the active conformation of the receptor when solubilized in detergent micelles. To this end, the receptor was purified using DDM, DDM/CHAPS, or the short hydrocarbon chain lipid 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC, di-6:0PC). After solubilization in DDM, DDM/CHAPS, or DHPC micelles, although A 2AR was found to retain its native-like fold, its binding ability was significantly compromised compared to DDM or DDM/CHAPS with CHS. It therefore appears that although cholesterol is not needed for A 2AR to retain a native-like, α-helical conformation, it may be a critical component for high affinity ligand binding. Further, this result suggests that the conformational differences between the active and inactive protein may be so subtle that commonly used spectroscopic methods are unable to differentiate between the two forms, highlighting the need for activity measurements. Furthermore, the studies presented inmore » this paper also underline the importance of the protein’s purification history; i.e., detergents that interact with the protein during purification affect the ligand binding properties of the receptor in an irreversible manner.« less
Authors:
 [1] ;  [1] ;  [2] ;  [3]
  1. Univ. of Delaware, Newark, DE (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
  3. Univ. of Delaware, Newark, DE (United States); Tulane Univ., New Orleans, LA (United States)
Publication Date:
OSTI Identifier:
1279449
Grant/Contract Number:
AC05-00OR22725; AC05 00OR2275
Type:
Accepted Manuscript
Journal Name:
Protein Expression and Purification
Additional Journal Information:
Journal Volume: 124; Journal ID: ISSN 1046-5928
Publisher:
Elsevier
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; GPCR; lipids; detergents; ligand binding; cholesterol