We have demonstrated histidine kinase activity in the ETR1 protein. We hypothesize that ETR1 could function analogously to the bacterial sensor proteins, with ethylene binding regulating activity of the histidine kinase domain. This may regulate some aspects of ethylene signaling. There are some significant differences between ETR1 and other members of this family. Some members have response regulator domains while others do not.
Some members have three transmembrane domains, while others have four.
Some members have highly conserved histidine kinase domains, while other members show significant divergence and lack residues considered essential for activity. How these isoforms function in ethylene signaling is being studied using a combination of biochemical, molecular, and genetic techniques. The information presented here represents the efforts of several labs that investigate ethylene signal transduction in Arabidopsis. Our interest is in the function of the histidine kinase domain. Listed below some of the other labs and their areas of interest.