Abstract:The COP1 (constitutively photomorphogenic 1) protein is a nuclear pro
tein with a molecular weight of 76 kD,which contains three recognizable structural domains: ring finger zinc binding domain, the putative coiled_coil region, and the domain with multiple WD_40 repeats. The protein is a repressor of photomorphogenic development and a light_regulated developmental molecular switch. In the dark, COP1 accumulates in the nucleus and represses photomorphogenic development, and the light diminishes the abundance of COP1 and abrogates its activity. The nucleocytoplasmic partitioning of COP1 are regulated by a number of factors, COP1 acts as a master regulator of specific transcription factors within the nucleus, it interactive with some specific transcription factors and regulate the constitutively photomorphogenic development. A mammalian COP1 that contains all the structural features present in plant COP1 was isolated and identified, which suggest that COP1 may share a common mode of action between higher plants and mammals in regulating development and cellular signaling.