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Phytochrome signaling mechanisms.
MedLine Citation:
PMID:  22303272     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
Phytochromes are red (R)/far-red (FR) light photoreceptors that play fundamental roles in photoperception of the light environment and the subsequent adaptation of plant growth and development. There are five distinct phytochromes in Arabidopsis thaliana, designated phytochrome A (phyA) to phyE. phyA is light-labile and is the primary photoreceptor responsible for mediating photomorphogenic responses in FR light, whereas phyB-phyE are light stable, and phyB is the predominant phytochrome regulating de-etiolation responses in R light. Phytochromes are synthesized in the cytosol in their inactive Pr form. Upon light irradiation, phytochromes are converted to the biologically active Pfr form, and translocate into the nucleus. phyB can enter the nucleus by itself in response to R light, whereas phyA nuclear import depends on two small plant-specific proteins FAR-RED ELONGATED HYPOCOTYL 1 (FHY1) and FHY1-LIKE (FHL). Phytochromes may function as light-regulated serine/threonine kinases, and can phosphorylate several substrates, including themselves in vitro. Phytochromes are phosphoproteins, and can be dephosphorylated by a few protein phosphatases. Photoactivated phytochromes rapidly change the expression of light-responsive genes by repressing the activity of CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1), an E3 ubiquitin ligase targeting several photomorphogenesis-promoting transcription factors for degradation, and by inducing rapid phosphorylation and degradation of Phytochrome-Interacting Factors (PIFs), a group of bHLH transcription factors repressing photomorphogenesis. Phytochromes are targeted by COP1 for degradation via the ubiquitin/26S proteasome pathway.
Authors:
Jigang Li; Gang Li; Haiyang Wang; Xing Wang Deng
Publication Detail:
Type:  Journal Article     Date:  2011-08-29
Journal Detail:
Title:  The Arabidopsis book / American Society of Plant Biologists     Volume:  9     ISSN:  1543-8120     ISO Abbreviation:  Arabidopsis Book     Publication Date:  2011  
Date Detail:
Created Date:  2012-02-03     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101214894     Medline TA:  Arabidopsis Book     Country:  United States    
Other Details:
Languages:  eng     Pagination:  e0148     Citation Subset:  -    
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