( Discovery likely to streamline drug and...)Hopkins scientists uncover 'tags' that force proteins to cell surface

Johns Hopkins scientists have discovered internal "shipping labels" that allow -- and perhaps force -- hundreds if not thousands of proteins to get to the surface of cells and stay there. Two natural proteins that use one of these "tags" are the ion channel that lets heart cells contract on cue, and the docking point that allows HIV, the virus that causes AIDS, into cells, the researchers discovered.

Because proteins on the cell surface are "lock-on" sites for drugs and other molecules, as well as triggers of immune reactions, the findings, described in the Sept. 11 advance online publications of Nature Cell Biology, might revolutionize efforts in drug and vaccine development, says the Hopkins team.

"A typical step in drug development is to get cells in a dish to express the protein you want to target with drugs, and then to test thousands of molecules to see which ones interact with the protein and have the effect you want," says the study's senior author, Min Li, Ph.D., a professor of neuroscience at the High Throughput Biology Center of the Johns Hopkins' Institute for Basic Biomedical Sciences.

"But if you can't get the protein to the cell surface, you can't use this screening technique. If we can force proteins to the cell surface, we can overcome obstacles that have prevented laboratory study of some really important proteins," says Li. The application of these surface tags to force protein transportation to the cell surface is the subject of a Patent Cooperation Treaty (PCT) patent application submitted by The Johns Hopkins University.

From among 25 billion randomly created, eight-building-block-long protein bits, postdoctoral fellow Sojin Shikano uncovered 65 that forced a normal protein to leave the cell's protein-building factory and go to the cell surface. By searching sequences of known human proteins, the researchers then identified those that use variatio
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Source:Johns Hopkins Medical Institutions