Ethylene-Binding Activity, Gene-Expression Levels, and Receptor-System Output for Ethylene-Receptor Family Members from Arabidopsis and Tomato
Ethylene signaling in plants is mediated by a family of ethylene receptors related to bacterial two-component regulators. Expression in yeast of ethylene-binding domains from the five receptor isoforms from Arabidopsis thaliana and five-receptor isoforms from tomato confirmed that all members of the family are capable of high-affinity ethylene-binding activity. All receptor isoforms displayed a similar level of ethylene binding on a per unit protein basis, while members of both subfamily I and subfamily II from Arabidopsis showed similar slow-release kinetics for ethylene. Quantification of receptor-isoform mRNA levels in receptor-deficient Arabidopsis lines indicated a direct correlation between total message level and total ethylene-binding activity in planta. Increased expression of remaining receptor isoforms in receptor-deficient lines tended to compensate for missing receptors at the level of mRNA expression and ethylene-binding activity, but not at the level of receptor signaling, consistent with specialized roles for family members in receptor signal output.
Brad M. Binder, Ronan C. O'Malley, Fernando I. Rodriguez, Jeffrey J. Esch, Philip O'Donnell, Harry J. Klee, and Anthony B. Bleecker. "Ethylene-Binding Activity, Gene-Expression Levels, and Receptor-System Output for Ethylene-Receptor Family Members from Arabidopsis and Tomato" The Plant Journal 41.5 (2005): 651-659.