Understanding how proteins fold could lead to the design of new proteins for highly specific functions, or new therapeutic drugs.

Researchers Susan Marqusee and Carlos Bustamante decided to investigate this problem one protein at a time.

Grabbing both ends of a single protein, they pulled and slowly unbent the protein, then gradually let it relax into its original 3-D shape.

The paper in today's Journal of Biological Chemistry by Professor of Biochemistry and Molecular Biology William Dowhan, Ph.D., and colleagues shows that phospholipids, which make up the permeable barrier of cell membranes, play a direct role in the folding of membrane proteins – proteins that penetrate the membrane or bind to either side of it.

"What we've demonstrated again is that it's not just a membrane protein's genetically determined sequence that dictates how it folds so that it can function properly. Its lipid environment also plays a role," Dowhan said. "People used to assume that specific lipids made no difference."

In the JBC paper, Dowhan and colleagues looked at how a protein called GabP, which transports an amino acid across the membrane of the bacterium E. coli, is affected by the presence of a phospholipid named phosphatidylethanolamine, or PE for short.

The array offers scientists a cutting edge research tool allowing them to analyze the specificities of glycan binding proteins (GBP's), which function through their binding to such sugar chains.

Research appearing in the Oct. 8 issue of the Journal of Molecular Biology, describes a new technique that may help scientists predict which proteins are prone to misfold and at what point the folding process is likely to break down. The research could support efforts to find the causes for diseases involving amyloids, and it could prove useful for researchers studying proteins involved in even more prevalent diseases like cancer and heart disease.

"We know now that most diseases involve proteins going wrong in one of two ways," said lead researcher Cecilia Clementi, assistant professor of chemistry at Rice University. "In the first, proteins don't function correctly because they fold into the wrong shape. This is something we see in sickle-cell anemia, for instance, because of genetic flaws that cause the amino acid sequence to be incorrectly synthesized.

"The second way proteins go wrong is by not folding at all, which is what we find in diseases involving amyloids. In these situations, the misfolded proteins assemble together into macroscopic aggregates."

1 Research Unit for Molecular Medicine, Aarhus University Hospital and Faculty of Health Sciences, Denmark

2 Institute of Human Genetics, University of Aarhus, Denmark

3 Department of Biological Sciences and BioX Program, Stanford University, CA, USA

4 Department of Cardiology, Aarhus University Hospital, Denmark

S. Vang, Research Unit for Molecular Medicine, Aarhus University Hospital, Skejby Sygehus, Brendstrupgaardsvej, DK-8200 Århus N, Denmark Fax: +45 89496018 Tel: +45 89495150 E-mail: vang@ki.au.dk

Hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) are the most common hereditary cardiac conditions. Both are frequent causes of sudden death and are often associated with an adverse disease course. Alpha-cardiac actin is one of the disease genes where different missense mutations have been found to cause either HCM or DCM. We have tested the hypothesis that the protein-folding pathway plays a role in disease development for two actin variants associated with DCM and six associated with HCM. Based on a cell-free coupled translation assay the actin variants could be graded by their tendency to associate with the chaperonin TCP-1 ring complex/chaperonin containing TCP-1 (TRiC/CCT) as well as their propensity to acquire their native conformation

"What we've developed is a simple and inexpensive sensor for determining when a protein changes its conformation," said study co-author Richard N. Zare, the Marguerite Blake Wilbur Professor in Natural Science in Stanford's Department of Chemistry. According to Zare, the new sensor may eventually provide biomedical researchers a fast, affordable method for detecting antibodies and other disease-related proteins.

The familial amyloidoses, on which the researchers focused their study, are caused by various mutations to a human protein called transthyretin (TTR). These mutations render transthyretin unstable and predisposed to misfolding from a normal, safe structure into dangerous, sticky ones that glom together and form microscopic fibrils, which then cluster to form larger amyloid plaques that deposit in peripheral nerves, organs, and sometimes in the central nervous system.

Strangely, some TTR mutations cause the fibrils to target the heart, others cause the fibrils to form in the peripheral nervous system, and still others cause the fibrils to form in the gut or in the brain. In the latest issue of the journal Cell, the Scripps Research team is describing the chemical and biological basis for this tissue selectivity.

It is not only, say the scientists, that certain tissues like the brain are more susceptible to the amyloid plaques because they are specifically targeted by misfolded TTR proteins, but rather because cells that secrete proteins into these tissues are the ones that secrete the bad proteins most efficiently.

"Most of the destabilized TTR variants tend to be secreted within susceptible tissues just as efficiently as normal TTR proteins, even though they are substantially destabilized," says Scripps Research Professor Jeffery W. Kelly, Ph.D., who led the research with Scripps Research Professor William E. Balch, Ph.D. Kelly is the Lita Annenberg Hazen Professor of Chemistry, a member of The Skaggs Institute for Chemical Biology, and Vice President of Academic Affairs at The Scripps Research Institute.

"The ability of the cell to efficiently release misfolded protein provides a striking and unanticipated new view of the operation of cellular secretion pathways," says Balch, who is a professor in Scripps Research's Department of Cell Biology and the Institute for Childhood and Neglected Diseases. "These results suggest that we may be able to correct these diseases by small molecules that target fundamental rules guiding protein folding and secretory pathway function."

Amyloidosis is All in How the Protein Folds

For decades, scientists have known that proteins have the propensity to fold into a particular three-dimensional structure based on the particular sequence of amino acids the body strings together. Scientists have also known that the structure of a protein is essential for the protein's function, and that an unfolded protein may not be functional. In the last few years, they have also become increasingly aware of the danger of protein misfolding and misassembly.

"What we've developed is a simple and inexpensive sensor for determining when a protein changes its conformation," said study co-author Richard N. Zare, the Marguerite Blake Wilbur Professor in Natural Science in Stanford's Department of Chemistry. According to Zare, the new sensor may eventually provide biomedical researchers a fast, affordable method for detecting antibodies and other disease-related proteins. Acid and base