Transcription activator that recognizes and binds to the DNA consensus sequence 5'-CACGCGC-3'. Activates the expression of FHY1 and FHL involved in light responses. When associated with PHYA, protects it from being recognized and degraded by the COP1/SPA complex. Positive regulator of chlorophyll biosynthesis via the activation of HEMB1 gene expression. Homodimer and heterodimer with FAR1. Interacts (via N-terminus) with PIF1 and with underphosphorylated PHYA. Down-regulated after exposure to far-red light. Subject to a negative feedback regulation by PHYA signaling. Up-regulated by white light. The FAR1 domain is involved in direct DNA binding, the SWIM-type zinc finger is essential for transcriptional activation activity and both the MULE and SWIM domains are essential for dimerization. Reduced protochlorophyllide levels in darkness and less photobleaching in the light. Belongs to the FHY3/FAR1 family.