Carnegie Mellon scientists develop fluorescent proteins for live cell imaging, biosen...(e cell the FAP technology provides an ex...)

The FAP is a specialized single chain antibody (scFv), a recombinant fragment of full-size antibody proteins that the human immune system uses to identify intruders like bacteria or viruses. The Carnegie Mellon scientists screened billions of scFvs to look for those that bound specifically to either of two fluorogens, malachite green and thiazole orange. The team found several scFvs that, when bound to the fluorogen, emitted bright fluorescent signals. They termed these scFvs fluorogen activating proteins.

These FAPs are the essential first step in developing molecular biosensors that will monitor dynamic changes occurring within cells, said Alan Waggoner, professor of biological sciences and director of the Molecular Biosensor and Imaging Center (MBIC). The ultimate goal is to put molecular biosensors based on FAP technology inside cells, but this current work is immediately useful. We have used the FAPs in conjunction with several fluorogens to visualize proteins at the cell surface and are now using the technology to image proteins inside cells.

The new FAPs are an extension of the genetic approach made popular by the advent of fluorescent proteins, such as green fluorescent protein (GFP), more than a decade ago. GFPs, once expressed in cells, are always aglow when visualized by scientists using special light sources and microscopes. The Carnegie Mellon team has taken GFP technology one step further with the novel FAPs and associated fluorogens, they can control fluorescence in space and time.

The beauty of our system is that we can make FAPs with genetic variations so that we can co-express distinct FAPs within a cell. We can also make synthetic variations of the fluorogen that have different fluorescent and binding properties. Together, these modifications will allows us to image multiple colors insid
'/>"/>