The good side of a maligned protein

cientists have discovered a new function for amyloid precursor protein (APP), a protein linked to Alzheimer’s disease. The finding may reveal how APP gets mixed up with the enzymes that make it go bad. APP has an evil reputation. The and secretases transform it into amyloidpeptide, a component of the plaques that riddle the brain in Alzheimer’s disease. Previous work by Larry Goldstein (Univesity of California, San Diego, CA) and coworkers suggested that APP normally links to kinesin, a protein that tows vesicles and organelles around the cell. Now Goldstein and colleagues have bolstered this hypothesis by examining neurons from APP-deficient mice. They found that the protein cargoes usually transported by kinesin couldn’t travel along the axon, whereas proteins not hauled by kinesin could. The researchers conclude that APP serves as a trailer hitch, coupling the membrane of a vesicle or organelle to kinesin. It turns out that two of the proteins moved by kinesin are the S