Figure 9.

Schematic Models Show the Nuclear Behaviors of Phytochromes.

The proxy model summarizes how phytochromes (phys) regulate gene expression by controlling the availability of transcription factors (TF). The escort model suggests that phyA and phyB directly associate with gene promoters by interacting with TF and coregulators (X). Consequently, phyA is directly involved in multiple plant responses that are coordinated with the FR signal. n represents different TFs or Xs involved in the phyA signaling.