PHYTOCHROME RAPIDLY REGULATED1
Protein DomainPHYTOCHROME RAPIDLY REGULATED1 (PAR1) is a non-DNA-binding atypical helix-loop-helix (HLH) inhibitor implicated in light-regulated transcriptional control in plants. In the cited study, PAR1 suppresses cell elongation by interfering with the DNA-binding activity of the bHLH transcription factor CIB1.