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Updated: Feb 10, 2026

In Vitro Analysis of E3 Ubiquitin Ligase Function
Published on: May 14, 2021
Photoreceptor-mediated regulation of the COP1/SPA E3 ubiquitin ligase
1Department of Botany and Plant Biology, Section of Biology, Faculty of Sciences, University of Geneva, CH-1211 Geneva 4, Switzerland; Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, Geneva, Switzerland.
Abstract:
Plants have evolved specific photoreceptors that capture informational cues from sunlight. The phytochrome, cryptochrome, and UVR8 photoreceptors perceive red/far-red, blue/UV-A, and UV-B light, respectively, and control overlapping photomorphogenic responses important for plant growth and development. A major repressor of such photomorphogenic responses is the E3 ubiquitin ligase formed by CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) and SUPPRESSOR OF PHYA-105 (SPA) proteins, which acts by regulating the stability of photomorphogenesis-promoting transcription factors. The direct interaction of light-activated photoreceptors with the COP1/SPA complex represses its activity via nuclear exclusion of COP1, disruption of the COP1-SPA interaction, and/or SPA protein degradation. This process enables plants to integrate different light signals at the level of the COP1/SPA complex to enact appropriate photomorphogenic responses according to the light environment.
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