Scientists devise method to study membrane proteins

Apr 14, 2004

Scientists at the University of Virginia Health System have come up with a protocol to extract proteins from membranes by using chemicals that allow them to be reversibly folded and refolded. The proteins can then be studied using crystallography or nuclear magnetic resonance imaging. Their work is detailed in the March 23 issue of the “Proceedings of the National Academy of Sciences” (PNAS) and also on the cover of the journal. The paper can be found on the web at: http://www.pnas.org/cgi/content/full/101/12/4065.

“The majority of drugs on the market today are effective because they work on membrane proteins, but our basic knowledge about these proteins lags far behind that of water-soluble proteins,” said Lukas Tamm, professor of molecular physiology and biological physics at U.Va. “We need to develop systems to get enough of these membrane proteins expressed in a cell culture so we can measure their thermodynamic, or energetic, stability,” Tamm said. “This is of practical interest in designing proteins for therapeutic applications because the proteins need to be kept around for a long time. This protocol developed at U.Va. shows for the first time that these proteins can be taken out of their membrane environment and put back in without losing function,” Tamm said. “We also found that the thermodynamic stability, or energy difference, between the folded and unfolded form of membrane proteins depends on the strength of the membrane “rubber band” that the proteins sit in. This energy difference can be predicted, one key variable in the drug discovery process.”

In a commentary on the findings, also in the March 23 issue of PNAS, James Bowie, a professor with the Molecular Biology Institute at the University of California, Los Angeles, wrote that “the new work opens another door to a more quantitative description of the energetics protein-protein and protein-lipid interactions in the (membrane) bilayer… We are finally beginning to obtain quantitative information about membrane protein structure.”

Working with U.Va. colleague Heedeok Hong, Tamm used an aqueous (water) system and a compound called urea, that unravels proteins, to carry out folding studies on a membrane protein of the Escherichia coli bacterium called OmpA. Tamm and Hong demonstrated that the folding of OmpA into the lipid bilayers of a membrane is a reversible, two-state process. They also demonstrated that elastic forces in bilayers, such as curvature stress, can affect the folding of membrane proteins.


Explore further: A 'movie' of ultrafast rotating molecules at a hundred billion per second

Related Stories

ESA image: Northwest Sardinia

59 minutes ago

This image over part of the Italian island of Sardinia comes from the very first acquisition by the Sentinel-2A satellite.

SemanticPaint system labels environment quickly online

1 hour ago

Ten researchers from University of Oxford, Microsoft Research Cambridge, Stanford, and Nankai University have presented a new approach to 3D scene understanding with a system which they dubbed SemanticPaint. ...

Recommended for you

To conduct, or to insulate? That is the question

Jul 02, 2015

A new study has discovered mysterious behaviour of a material that acts like an insulator in certain measurements, but simultaneously acts like a conductor in others. In an insulator, electrons are largely stuck in one place, ...

Soundproofing with quantum physics

Jul 02, 2015

Sebastian Huber and his colleagues show that the road from abstract theory to practical applications needn't always be very long. Their mechanical implementation of a quantum mechanical phenomenon could soon ...

Extreme lab at European X-ray laser XFEL is a go

Jul 02, 2015

The Helmholtz Senate has given the green light for the Association's involvement in the Helmholtz International Beamline (HIB), a new kind of experimentation station at the X-ray laser European XFEL in Hamburg, ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.