Figure 7.

Model Describing How CRY1 Regulates BR Signaling.

When BR is available, BES1 is largely dephosphorylated. In the dark (A), CRY1 is inactive and unable to inhibit BR signaling because it is not capable of interacting with dephosphorylated BES1. In the light (B), CRY1 is activated and interacts with dephosphorylated BES1 via the CRY1 N terminus (CNT1) to inhibit its DNA binding activity (left side). When BR is unavailable, BES1 is largely phosphorylated. Photoactivated CRY1 is not able to interact with phosphorylated BES1 (right side). Thicker and thinner red arrows indicate higher and lower levels of gene expression, respectively. +BR and −BR indicate the availability and unavailability of BR in plants, respectively. Larger and smaller font sizes for BES1 represent higher and lower levels of dephosphorylated or phosphorylated BES1, respectively.