Plants, animals share signaling system

For the first time, scientists have provided concrete evidence that endosome-mediated signaling occurs in plants, not just in animals, according to a new report in Genes and Development. "The fact that both [plants and animals] share some similarities in the endosomal signaling system means that this system is either much older than we could have ever assumed, or that plants have independently evolved the same solution to the same problem, a scenario that I favor," study author Niko Geldner of The Salk Institute in La Jolla, California, told The Scientist. Plants and animals evolved very different receptor sets since their split more than a billion years ago. In the past, researchers considered receptor endocytosis as purely a mechanism of signal inactivation and down regulation. However, research in animals in the last decade has demonstrated that some ligand-bound receptors actually need to be internalized and travel in endosomes for...