Understanding trends in GPCR Structural
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G-protein Coupled Receptors (GPCRs) are the largest family of membrane proteins and are responsible for the transmission of an extracellular signal to inside the cell, and are necessary for the senses of sight, smell, and taste(1). Importantly, approximately 34% of all drugs approved by the FDA target GPCR proteins, with many more currently in clinical trials(2). Thus, biochemical and structural studies of GPCR proteins are of paramount importance to drug discovery initiatives. Illustrating this point, the 2012 Nobel Prize in Chemistry was awarded to Robert Lefkowitz and Brian Kobilka for their pioneering work on understanding GPCR structure and function.
 
The crystal structure of the first GPCR protein, Bovine rhodopsin, was determined in 2000(3), and the first human GPCR structure, β2 adrenergic receptor, was determined in 2007(4). To date, structures of 67 unique GPCR proteins have been determined (2000 – April 2019), with the majority of these structures, 41, coming in just over the past five years. In this newsletter, we wanted to break down some of the trends in GPCR structural biology, and share with you what methods and detergents are most commonly used.

Eukaryotic expression systems are most commonly used for GPCR proteins, with insect cell systems (SF9 and High Five) being used the most often (85%), and HEK expression systems being used in 6% of the structures. For solubilization of GPCR proteins, the detergent DDM + CHS was used 73% of the time, while LMNG + CHS was used 9% of the time. The majority (58) of the unique GPCR structures were determined by the Lipidic Cubic Phase (LCP) crystallization method, with four of those using the LCP-SFX method(5). Additionally, Vapor Diffusion (4), NMR (2), Cryo-EM (2), and Bicelle (1) crystallization have also been used to determine structures of GPCR proteins. Almost all of the structures determined by LCP used a monoolein – cholesterol mixture as the host lipid. As with solubilization, there is little parity in the detergents used for structure determination, with DDM + CHS being used in about half of the structures (49%), and LMNG + CHS being used in a quarter of the structures (25%).

Tools from Anatrace and Molecular Dimensions for GPCR Structural Biology

To save you time, simplify your workflow, and increase your reproducibility, Anatrace offers premixed detergent solutions which are commonly used in GPCR structural studies:

  For LCP Crystallization, Anatrace and Molecular Dimensions offer a number of tools including:
 

 References:
  1. Rosenbaum DM, et al. (2009) Nature 459(7245), 356-363
  2. Hauser, AS, et al. (2017) Nat. Rev. Drug Discov. 16(12), 829-842
  3. Palczewski, K, et al. (2000) Science 289(5480), 739-745
  4. Cherezov, V, et al. (2007) Science 318(5854), 1258-1265
  5. Liu, W. et al. (2014) Philos Trans R Soc Lond B Biol Sci 369(1647), 20130314