Ethylene receptor related to bacterial two-component regulators. Acts as a redundant negative regulator of ethylene signaling. ATP + protein L-histidine = ADP + protein N-phospho-L-histidine. Binds 1 copper ion per dimer. Homodimer. Highly expressed in anthers and at lower levels in roots, leaves and hulls. Repressed by treatment with silver. Dwarf, chlorina and half sterility phenotypes. Belongs to the ethylene receptor family.