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. Author manuscript; available in PMC: 2012 Nov 1.
Published in final edited form as: Trends Cell Biol. 2011 Aug 17;21(11):664–671. doi: 10.1016/j.tcb.2011.07.002

Figure 3. Phy signaling pathways to turn on photomorphogenesis.

Figure 3

There are two major signaling pathways: first, in the “blue” pathway, phys de-repress the positively acting transcriptional regulators, including HY5, LAF1 and HFR1, by inhibiting the COP1 and DET1 containing CUL4 E3 ubiquitin ligases; Second, in the “orange” pathway, phys trigger the degradation of the negatively acting transcriptional regulators PIFs. The activity of PIFs could be enhanced by the COP1/DET1 through HFR1 repression; the protein stability of at least PIF3 is promoted by COP1 through an unknown mechanism. The recently identified HMR acts early in the pathways and is involved in the degradation of PIFs and phyA as well as the inhibition of DET1.