Evidence for functional conservation of a mammalian homologue of the light-responsive plant protein COP1

Curr Biol. 1999 Jul 1;9(13):711-4. doi: 10.1016/s0960-9822(99)80314-5.


Identified in Arabidopsis as a repressor of light-regulated development, the COP1 (constitutively photomorphogenic 1) protein is characterized by a RING-finger motif and a WD40 repeat domain [1]. The subcellular localization of COP1 is light-dependent. COP1 acts within the nucleus to repress photomorphogenic development, but light inactivates COP1 and diminishes its nuclear abundance [2]. Here, we report the identification of a mammalian COP1 homologue that contains all the structural features present in Arabidopsis COP1 (AtCOP1). When expressed in plant cells, a fusion protein comprising mammalian COP1 and beta-glucuronidase (GUS) responded to light by changing its subcellular localization pattern in a manner similar to AtCOP1. Whereas the mammalian COP1 was unable to rescue the defects of Arabidopsis cop1 mutants, expression of the amino-terminal half of mammalian COP1 in Arabidopsis interfered with endogenous COP1 function, resulting in a hyperphotomorphogenic phenotype. Therefore, the regulatory modules in COP1 proteins that are responsible for the signal-dependent subcellular localization are functionally conserved between higher plants and mammals, suggesting that mammalian COP1 may share a common mode of action with its plant counterpart in regulating development and cellular signaling.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Arabidopsis / chemistry*
  • Arabidopsis / growth & development
  • Arabidopsis Proteins*
  • Carrier Proteins / chemistry*
  • Carrier Proteins / physiology
  • Cells, Cultured
  • Glucuronidase / analysis
  • Humans
  • Light
  • Onions
  • Phenotype
  • Plant Proteins / chemistry*
  • Plant Proteins / physiology
  • Recombinant Fusion Proteins / chemistry*
  • Recombinant Fusion Proteins / physiology
  • Ubiquitin-Protein Ligases*


  • Arabidopsis Proteins
  • Carrier Proteins
  • Plant Proteins
  • Recombinant Fusion Proteins
  • AT2G32950 protein, Arabidopsis
  • Ubiquitin-Protein Ligases
  • Glucuronidase

Associated data

  • GENBANK/AF151110