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. Expressed in anthers and hulls. Belongs to the ethylene receptor family.