The activities of the E3 ubiquitin ligase COP1/SPA, a key repressor in light signaling
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Updated: Mar 3, 2026

In Vitro Analysis of E3 Ubiquitin Ligase Function
Published on: May 14, 2021
1Botanical Institute and Cluster of Excellence on Plant Sciences (CEPLAS), Biocenter, University of Cologne, Zülpicher Str. 47b, D-50674 Cologne, Germany.
Abstract:
Light is a critical signal to integrate plant growth and development with the environment. Downstream of photoreceptors, the E3 ubiquitin ligase COP1/SPA is a key repressor of photomorphogenesis which targets many positive regulators of light signaling, mainly transcription factors, for degradation in darkness. In light-grown plants COP1/SPA activity is repressed, allowing light responses to occur. This review provides an overview on our current knowledge on COP1/SPA repressor function, focusing in particular on the roles of the respective protein domains and the mechanisms of light-induced inactivation of COP1/SPA. Moreover, we summarize how COP1 activity is regulated by other interacting proteins, such as a SUMO E3 ligase and Phytochrome-Interacting Factors (PIFs), as well as by hormones. At last, several novel functions of COP1 that were recently revealed are included.
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