Lipid environment of membrane proteins in cryo-EM based structural analysis
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Cryoelectron microscopy (cryo-EM) in association with a single particle analysis method (SPA) is now a promising tool to determine the structures of proteins and their macromolecular complexes. The development of direct electron detection cameras and image processing technologies has allowed the structures of many important proteins to be solved at near-atomic resolution or, in some cases, at atomic resolution, by overcoming difficulties in crystallization or low yield of protein production. In the case of membrane-integrated proteins, the proteins were traditionally solubilized and stabilized with various kind of detergents. However, the density of detergent micelles diminished the contrast of membrane proteins in cryo-EM studies and made it difficult to obtain high-resolution structures. To improve the resolution of membrane protein structures in cryo-EM studies, major improvements have been made both in sample preparation techniques and in hardware and software developments. The focus of our review is on improvements which have been made in the various techniques for sample preparation for cryo-EM studies, with a specific interest placed on techniques for mimicking the lipid environment of membrane proteins.
KeywordsCryoelectron microscopy Membrane proteins Single particle analysis Lipid environment
This work was supported in part by Grant-in-Aid for Scientific Research on Priority Areas from the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT).
Compliance with ethical standards
Conflict of interest
Kazuhiro Mio declares that he has no conflicts of interest. Chikara Sato declares that he has no conflicts of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
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