Membrane Protein Crystallization: Techniques and Approaches by Creative Biostructure, Slides of Biology

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Membrane Protein

Crystallization

Membrane proteins play a vital role in many biological processes, and nearly 30% of proteins in

eukaryotic cells are known to be membrane proteins. They have proven to be difficult to study

due to their partially hydrophobic surfaces and lack of stability outside the lipid bilayer

environment that is critical for membrane protein structure and activity. Crystallization of these

proteins is notoriously challenging, which usually involves extensive detergent screening to

identify optimal conditions.

Creative Biostructure takes advantage of our membrane screening platform for effective

expression, solubilization, purification and crystallization of membrane proteins. For the past

few years, our scientists have been actively developing and optimizing methods for the study

of a variety of membrane proteins such as receptors, ion channels and transporters. The

crystallization of membrane proteins generally begins with the test of a large number of

possible crystallization reagents to identify the initial conditions, which are then subjected to

further optimization to obtain well-diffracting crystals. Creative Biostructure has designed in-

house 96-well sparse matrix screening systems specifically optimized for membrane proteins.

We generally use the two major strategies to promote diffraction quality crystals:

Lipidic cubic phases (LCP) are mainly formed by mixing the selected lipid with an

aqueous buffer at certain ratio and temperature, when the matrix becomes a

transparent and non-birefringent gel-like material. In the three-dimensional continuous

lipidic cubic phases such as the Pn3m phase, membrane proteins can freely diffuse in the

lipid, instead of being enclosed in detergent micelle. The proteins molecules can

therefore be concentrated to form well-ordered crystals.

Crystallization using bicelles is another successful in meso method. Bicelles are small

bilayer disks formed from a number of lipid: amphiphile combinations when mixed at

low temperature. They offer a native-like bilayer environment to the membrane proteins

enhancing the growth of type I crystals. Crystallization in bicelles can be carried out in a

traditional set up including the use of standard crystallization robotics and commercial

crystallization screens.

Thank you!

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membrane-protein-crystallization-549.htm