Ethylene perception and signaling: an evolutionary perspective.

Ethylene signal transduction, as revealed by studies in Arabidopsis, provides an interesting example of how information-processing systems have evolved in plants. The ethylene signal is perceived by a family of receptors composed of structural elements that are characteristic of bacterial signaling proteins. In plants, these receptors transmit the signal by interacting with proteins that are eukaryotic in origin. The ethylene sensor domain of the receptors forms a membrane-associated structure that uses a copper cofactor to bind ethylene. This novel protein motif appears to have originated early in the evolution of photosynthetic organisms.