The COP1-SPA1 interaction defines a critical step in phytochrome A-mediated regulation of HY5 activity.

Arabidopsis COP1 is a constitutive repressor of photomorphogenesis that interacts with photomorphogenesis-promoting factors such as HY5 to promote their proteasome-mediated degradation. SPA1 is a repressor of phytochrome A-mediated responses to far-red light. Here we report that COP1 acts as part of a large protein complex and interacts with SPA1 in ...
a light-dependent manner. We further demonstrate the E3 ubiquitin ligase activity of COP1 on HY5 in vitro and the alteration of that activity by SPA1. Thus, the COP1-SPA1 interaction defines a critical step in coordinating COP1-mediated ubiquitination and subsequent degradation of HY5 with PHYA signaling.
Mesh Terms:
Arabidopsis, Arabidopsis Proteins, Basic-Leucine Zipper Transcription Factors, Nuclear Proteins, Phytochrome, Phytochrome A, Ubiquitin-Protein Ligases
Genes Dev.
Date: Nov. 01, 2003
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