Cryogenic electron microscopy (Cryo-EM) is a microscopy technique applied to samples cooled to cryogenic temperatures. Samples are rapidly frozen (vitrified), preserving the sample in its native state. A transmission electron microscope (TEM) is then used to capture two-dimensional projections, which are combined to make a 3D model. The technique is applicable to a wide range of protein targets including membrane proteins, such as GPCRs and ion channels, and does not require crystallisation of the protein which allows flexible conformations to be observed.  

Cryo-EM is the method of choice for large proteins or protein complexes, particularly when crystallisation has proved challenging. Proteins with molecular weights >100 kDa are preferred, as proteins with smaller molecular weights can be challenging. However, this can often be overcome by the addition of fiducial markers.

Our in-house expert microscopists will generate Cryo-EM structures for your project using external state-of-the-art data collection facilities accessed through our partner agreements.

Advantages of Cryo-EM

• The rapid vitrification treatment of the sample maintains its closer-to-native state 
• A relatively small amount of sample material is required compared to X-ray crystallography
• Captures flexible conformations
• Can determine structures of heterogenous protein complexes
• No extensive construct optimisation required, such as removal of post-translational modifications 
• It does not require the protein to crystallise
• High sample purity is not required 
• Can be combined with our PoLiPa technology to generate structures of membrane proteins

Domainex also offers the complementary technique of X-ray crystallography and our experts can help you decide which is the best approach for your project.