查看文章

The COP9/signalosome complex is conserved from plant to mammalian cells. In Arabidopsis, it regulates the nuclear abundance of COP1, a transcriptional repressor of photomorphogenic development [1,2]. All COP (constitutive photomorphogenesis) mutants inappropriately express genes that are normally repressed in the dark. Eight subunits (Sgn1–Sgn8) of the homologous mammalian complex have been purified [3,4]. Several of these have been previously identified through genetic or protein interaction screens. No coherent model for COP9/signalosome function has yet emerged, but a relationship with cell-cycle progression by transcriptional regulation, protein localisation or protein stability is possible. Interestingly, the COP9/signalosome subunits possess domain homology to subunits of the proteasome regulatory lid complex [5,6]. Database searches indicate that only Sgn5/JAB1 is present in …