Ethylene receptor related to bacterial two-component regulators. Acts as negative regulator of ethylene signaling. May play a role in the regulation of flowering by up-regulating GI (GIGANTEA) and RCN1 and regulate starch accumulation by down-regulating the alpha-amylase AMY3D. ATP + protein L-histidine = ADP + protein N-phospho-L-histidine. Binds 1 copper ion per dimer. Homodimer. Chlorina phenotype (PubMed:16891544). Enhanced ethylene sensitivity (PubMed:19417056). Belongs to the ethylene receptor family.