"This particular tag and its closest relatives actually mark normal proteins for delivery to the cell surface," says Li. "In some diseases, a protein that should be on the cell surface isn't, and in the lab, sometimes it's proven impossible to get a protein to the cell surface in order to study it. The tags we've found might help us force proteins to the surface, which offers real hope for overcoming these hurdles."
Laboratory studies in which the tags might be used to force a protein of interest to the cell surface are likely to be widely used fairly quickly, but Li cautions that any potential clinical applications will require understanding exactly how the tag helps the protein's transportation.
Among the "problem proteins" are those that detect odors in the nose, and the protein that's faulty in cystic fibrosis. Being able to force these to the cell surface in laboratory dishes might enable identification of more potent scents or ways to help people who can't smell, or help uncover new strategies for treating CF.
Although many scientists would say that failure to get these proteins to the cell surface means the proteins weren't assembled properly in the cell, Li says that how and where proteins are made has a lot to do with the difficulties researchers have had.
For one, proteins are made deep inside the cell; the genetic instructions for building proteins are in the cell nucleus, and proteins are assembled in a nearby "factory" in the cell. Also, scientists have long known that proteins prefer to stay put in this factory, the endoplasmic reticulum, unless they contain specific transportation instructions, much like an internal shipping label.
To figure out what tiny sequences might label the protein for delivery to the cell su
Source:Johns Hopkins Medical Institutions