InterPro domain: IPR037766

This entry represents a group of plant proteins, including FHY1 (At2g37678) from Arabidopsis. Phytochrome A (phyA) is the photoreceptor in Arabidopsis that mediates the far-red light high radiance response. AtFHY1 is a key regulator of far red/red (FR/R) spectrum-specific responses by regulating phyA shuttling from the cytoplasm to the nucleus and by directly regulating the expression of some target genes. AtFHY1 phosphorylation is induced by the R signal, is part of the FR/R spectrum sensing mechanism that ensures its optimal response to specific light quality [ 1 ]. AtFHY1 also has an independent role in gene modulation and plant development under far-red light [ 2 ].

This entry also includes FHL (FHY1 Like). FHL is essential for light-regulated PHYA nuclear accumulation and subsequent PHYA phototropic signaling processes [ 3 , 4 , 5 ]. The transcription of FHY1 and FHL are controlled by FHY3 (Far-red elongated HYpocotyl 3) and FAR1 (FAr-red impaired Response 1), a related pair of transcription factors [ 6 ].

1. Phosphorylation of FAR-RED ELONGATED HYPOCOTYL1 is a key mechanism defining signaling dynamics of phytochrome A under red and far-red light in Arabidopsis. Plant Cell 24, 1907-20
2. Photoreceptor partner FHY1 has an independent role in gene modulation and plant development under far-red light. Proc. Natl. Acad. Sci. U.S.A. 111, 11888-93
3. Missense mutation in the amino terminus of phytochrome A disrupts the nuclear import of the photoreceptor. Plant Physiol. 158, 107-18
4. Nuclear phytochrome A signaling promotes phototropism in Arabidopsis. Plant Cell 24, 566-76
5. Arabidopsis fhl/fhy1 double mutant reveals a distinct cytoplasmic action of phytochrome A. Proc. Natl. Acad. Sci. U.S.A. 104, 10737-42
6. FHY1 mediates nuclear import of the light-activated phytochrome A photoreceptor. PLoS Genet. 4, e1000143