6qtw

Structural highlights

Function

[COP1_ARATH] E3 ubiquitin-protein ligase that acts as a repressor of photomorphogenesis and as an activator of etiolation in darkness. E3 ubiquitin ligases accept ubiquitin from an E2 ubiquitin-conjugating enzyme in the form of a thioester and then directly transfers the ubiquitin to targeted substrates. Represses photomorphogenesis in darkness by mediating ubiquitination and subsequent proteasomal degradation of light-induced transcription factors such as HY5, HYH and LAF1. Down-regulates MYB21, probably via ubiquitination process. Light stimuli abrogate the repression of photomorphogenesis, possibly due to its localization to the cytoplasm. Could play a role in switching between skotomorphogenetic and photomorphogenetic pathways.^{[1] [2]} [CRY1_ARATH] Mediates blue light-induced gene expression through the inhibition of COP1-mediated degradation of the transcription factor BIT1. Involved in blue light-dependent stomatal opening, CHS gene expression, inhibition of stem growth and increase of root growth.^{[3] [4] [5] [6] [7]}

References

1. ↑ Shin B, Choi G, Yi H, Yang S, Cho I, Kim J, Lee S, Paek NC, Kim JH, Song PS, Choi G. AtMYB21, a gene encoding a flower-specific transcription factor, is regulated by COP1. Plant J. 2002 Apr;30(1):23-32. PMID:11967090
2. ↑ Holm M, Ma LG, Qu LJ, Deng XW. Two interacting bZIP proteins are direct targets of COP1-mediated control of light-dependent gene expression in Arabidopsis. Genes Dev. 2002 May 15;16(10):1247-59. PMID:12023303 doi:http://dx.doi.org/10.1101/gad.969702
3. ↑ Malhotra K, Kim ST, Batschauer A, Dawut L, Sancar A. Putative blue-light photoreceptors from Arabidopsis thaliana and Sinapis alba with a high degree of sequence homology to DNA photolyase contain the two photolyase cofactors but lack DNA repair activity. Biochemistry. 1995 May 23;34(20):6892-9. PMID:7756321
4. ↑ Ahmad M, Jarillo JA, Smirnova O, Cashmore AR. Cryptochrome blue-light photoreceptors of Arabidopsis implicated in phototropism. Nature. 1998 Apr 16;392(6677):720-3. PMID:9565033 doi:http://dx.doi.org/10.1038/33701
5. ↑ Mao J, Zhang YC, Sang Y, Li QH, Yang HQ. From The Cover: A role for Arabidopsis cryptochromes and COP1 in the regulation of stomatal opening. Proc Natl Acad Sci U S A. 2005 Aug 23;102(34):12270-5. Epub 2005 Aug 10. PMID:16093319 doi:http://dx.doi.org/0501011102
6. ↑ Canamero RC, Bakrim N, Bouly JP, Garay A, Dudkin EE, Habricot Y, Ahmad M. Cryptochrome photoreceptors cry1 and cry2 antagonistically regulate primary root elongation in Arabidopsis thaliana. Planta. 2006 Oct;224(5):995-1003. Epub 2006 May 9. PMID:16703358 doi:http://dx.doi.org/10.1007/s00425-006-0280-6
7. ↑ Hong SH, Kim HJ, Ryu JS, Choi H, Jeong S, Shin J, Choi G, Nam HG. CRY1 inhibits COP1-mediated degradation of BIT1, a MYB transcription factor, to activate blue light-dependent gene expression in Arabidopsis. Plant J. 2008 Aug;55(3):361-71. Epub 2008 Apr 4. PMID:18397371 doi:http://dx.doi.org/TPJ3508