Cell Membrane Proteins Feel Long-Range Forces
News Aug 30, 2012
Proteins embedded in the lipid membranes of cells feel long-range attractive forces in specific patterns that mediate the proteins' behavior -- for example, assisting in the clumping sequences in response to allergens, such as pollen, that eventually lead to the inevitable sneeze.
The research from Cornell, led by professor of physics Jim Sethna, has been accepted for publication in Physical Review Letters.
The researchers were inspired by a recent discovery that cell membranes can separate into two liquid phases, much like oil and water, in fractal-like patterns. The physical fluctuations that result lead to remarkably long-range attractions between certain proteins, depending on the fractal patterns.
These changes take place at the so-called critical point of the liquid-liquid phase separation of the cell membrane, which is the subtle temperature and composition point at which the two phases separate. The proteins sitting in this membrane, at this critical point, are able to feel forces 20 nanometers apart, the physicists predict -- a notable distance at those scales.
"We were intrigued that it seems like biology does want to tune itself closely to this critical point," said graduate student and co-author Ben Machta.
The experiments built on previous work by former postdoctoral associate and co-author Sarah Veatch, who had studied cellular membranes of immune cells and demonstrated their liquid-liquid phase separations.
The work was supported by the National Science Foundation and the National Institutes of Health.
How Ribosomes Shape the ProteomeNews
Cells are crowded with macromolecules, which limits the diffusion of proteins, especially in prokaryotic cells without active transport in the cytoplasm. While investigating the relationship between crowding, ionic strength and protein diffusion, biochemists made a fascinating discovery: positively charged proteins stick to the surface of ribosome complexes. This explains why most water-soluble proteins carry an overall negative charge.READ MORE
Public Resource of Cellular Effects of Drugs and Genes Boosts Drug Discovery and Offers Insights Into Protein FunctionNews
Researchers have taken the Connectivity Map — a widely used resource of tools and data — to new heights with a massively scaled-up version including more cell types, more perturbations, and more types of data, including proteomic and cellular imaging data. For this new platform, the researchers have also improved its accessibility for the scientific community, enabling studies of small molecule and gene function and informing clinical trials.READ MORE