Switching mechanism of monomeric G proteins 

“On” state, switch I and switch II, are bound to the terminal γ phosphate of GTP with the backbone amide groups of conserved T & G.

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Phytochrome interacting factors (PIFs) are a family of proteins that act primarily as negative regulators of photomorphogenic responses.

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PIFs promote etiolated development in the dark (skotomorphogenesis) primarily by serving as transcriptional activators of dark induced genes

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Red light-induced Pfr formation initiates the degradation of PIF proteins through phosphorylation, followed by degradation via the proteasome complex

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CONSTITUTIVE PHOTOMORPHOGENESIS1 (COP1), another negative regulator of photomorphogenesis, is a component of the E3 ubiquitin ligase complex that targets photomorphogenesis-promoting proteins for degradation such as phyA, phyB.

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COP1 is found in the nucleus in the dark and in the cytoplasm in the light. COP1 movement into the nucleus in the dark requires the COP9 signalosome (CSN) complex