Receptors ethylene-binding

Although apparently derived from the bacterial two-component signaling system, the ethylene system in Arabidopsis is different in that the His kinase activity that defines component 1 in bacteria is not essential to the transduction in Arabidopsis. The genome of the cyanobacterium Anabaena encodes proteins with both an ethylene-binding domain and an active His kinase domain. It seems likely that in the course of evolution, the ethylene receptor of vascular plants was derived from that of a cyanobacterial endosymbiont, and that the bacterial His kinase became a Ser/Thr kinase in the plant. 

By far the most exciting development of this work was the demonstration by Schaller and Bleecker [31] that transformation of yeast with the wild type ETR gene conferred the ability to bind ethylene in a saturable and reversible manner and with an appropriate Kp (2.4xl0 M). These results taken together with those outlined above provide almost conclusive evidence that the ETR gene product is indeed an ethylene receptor. In the same work expression of truncated forms of ETRI in yeast provided further evidence that the N-terminal hydrophobic domain of the protein is the site of ethylene binding. 

Ethylene Binding Receptors — Is There More Than One ... 

Ethylene action depends on binding to a receptor site that has a low affinity for other olefines. Oxygen is required for the response, which is competitively inhibited by carbon dioxide. 

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