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Gene Review

PHOT1  -  phototropin 1

Arabidopsis thaliana

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Disease relevance of PHOT1

  • Here, we have transformed the phot1 phot2 (phot1-5 phot2-1) double mutant with PHOT expression constructs driven by the cauliflower mosaic virus 35S promoter [1].
  • Moreover, the data obtained from full-length Arabidopsis phot1 and phot2 expressed in insect cells closely resemble those obtained for the tandem LOV-domain fusion proteins expressed in E. coli [2].
  • A prokaryotic protein, YtvA from Bacillus subtilis, was found to possess a light, oxygen, voltage (LOV) domain sharing high homology with the photoactive, flavin mononucleotide (FMN)-binding LOV domains of phototropins (phot), blue-light photoreceptors for phototropism in higher plants [3].

High impact information on PHOT1


Biological context of PHOT1

  • In Arabidopsis thaliana, phototropism of seedling and plant stems is under the control of two paralogous genes, PHOT1 and PHOT2, that encode different phototropins with partially redundant light response qualities [8].
  • In vitro experiments indicate that cross phosphorylation can occur between functional phot2 and inactivated phot1 molecules [1].
  • Similarly, transformants carrying a PHOT transgene with both LOV domains inactivated developed strong curvatures toward high fluence rate blue light [1].
  • Surprisingly, the only significant genotype-by-environment interaction for fitness occurred during emergence: genotypes blind to dim blue light (phot1 and nph3) had poor emergence in the open, but not in the shade [8].
  • Consistent with their different fluence rate sensitivities, phot1 and phot2 signaling pathways affected fitness at discrete life-cycle stages [8].

Anatomical context of PHOT1

  • The Arabidopsis gene NPL1 (ref. 2) is a paralogue of the NPH1 gene, which encodes phototropin, a photoreceptor for phototropic bending [6].
  • Although phot1 is localized consistently to the plasma membrane region in etiolated seedlings, a fraction becomes released to the cytoplasm in response to blue light [9].
  • Moreover, increased ATP hydrolysis and the binding of 14-3-3 protein to the H+-ATPase were found in response to blue light in guard cell protoplasts from the wild type, but not from the phot1 phot2 double mutant [10].

Associations of PHOT1 with chemical compounds


Physical interactions of PHOT1

  • The PHOT1 gene product interacts with the NPH3 gene product to cause phototropic bending over a broad range of light intensity, from very weak light in the soil to stronger light in the aerial environment [8].

Regulatory relationships of PHOT1


Other interactions of PHOT1


Analytical, diagnostic and therapeutic context of PHOT1

  • Thus, these results suggest that phot1 and phot2 choose different signal transducers to induce three responses: phototropic response of hypocotyl, stomatal opening, and chloroplast relocation [16].
  • These results unravel the stoma autonomous function in the blue light response and illuminate the implication of PHOT1 and/or PHOT2 in such response [20].
  • These structural homologies indicate that NPH1 homologues can be grouped into two classes namely "NPH1 type" and "NPL1 type". Northern blot analysis showed that OsNPH1a was strongly expressed in coleoptiles, whereas OsNPH1b was highly expressed in leaves of dark-grown rice seedlings [21].
  • In this study, we compared light-induced structural changes of the LOV1 and LOV2 domains of a phototropin, Adiantum phytochrome3 (phy3), by means of UV-visible and Fourier transform infrared (FTIR) spectroscopy [22].


  1. Physiological roles of the light, oxygen, or voltage domains of phototropin 1 and phototropin 2 in Arabidopsis. Cho, H.Y., Tseng, T.S., Kaiserli, E., Sullivan, S., Christie, J.M., Briggs, W.R. Plant Physiol. (2007) [Pubmed]
  2. Photochemical properties of the flavin mononucleotide-binding domains of the phototropins from Arabidopsis, rice, and Chlamydomonas reinhardtii. Kasahara, M., Swartz, T.E., Olney, M.A., Onodera, A., Mochizuki, N., Fukuzawa, H., Asamizu, E., Tabata, S., Kanegae, H., Takano, M., Christie, J.M., Nagatani, A., Briggs, W.R. Plant Physiol. (2002) [Pubmed]
  3. First evidence for phototropin-related blue-light receptors in prokaryotes. Losi, A., Polverini, E., Quest, B., Gärtner, W. Biophys. J. (2002) [Pubmed]
  4. ZEITLUPE encodes a novel clock-associated PAS protein from Arabidopsis. Somers, D.E., Schultz, T.F., Milnamow, M., Kay, S.A. Cell (2000) [Pubmed]
  5. Responses of ferns to red light are mediated by an unconventional photoreceptor. Kawai, H., Kanegae, T., Christensen, S., Kiyosue, T., Sato, Y., Imaizumi, T., Kadota, A., Wada, M. Nature (2003) [Pubmed]
  6. Phototropin-related NPL1 controls chloroplast relocation induced by blue light. Jarillo, J.A., Gabrys, H., Capel, J., Alonso, J.M., Ecker, J.R., Cashmore, A.R. Nature (2001) [Pubmed]
  7. Arabidopsis NPH3: A NPH1 photoreceptor-interacting protein essential for phototropism. Motchoulski, A., Liscum, E. Science (1999) [Pubmed]
  8. An experimental test of the adaptive evolution of phototropins: blue-light photoreceptors controlling phototropism in Arabidopsis thaliana. Galen, C., Huddle, J., Liscum, E. Evolution (2004) [Pubmed]
  9. Cellular and subcellular localization of phototropin 1. Sakamoto, K., Briggs, W.R. Plant Cell (2002) [Pubmed]
  10. Biochemical characterization of plasma membrane H+-ATPase activation in guard cell protoplasts of Arabidopsis thaliana in response to blue light. Ueno, K., Kinoshita, T., Inoue, S., Emi, T., Shimazaki, K. Plant Cell Physiol. (2005) [Pubmed]
  11. Blue light-induced kinetics of H+ and Ca2+ fluxes in etiolated wild-type and phototropin-mutant Arabidopsis seedlings. Babourina, O., Newman, I., Shabala, S. Proc. Natl. Acad. Sci. U.S.A. (2002) [Pubmed]
  12. Phototropin LOV domains exhibit distinct roles in regulating photoreceptor function. Christie, J.M., Swartz, T.E., Bogomolni, R.A., Briggs, W.R. Plant J. (2002) [Pubmed]
  13. Blue light-regulated molecular switch of Ser/Thr kinase in phototropin. Matsuoka, D., Tokutomi, S. Proc. Natl. Acad. Sci. U.S.A. (2005) [Pubmed]
  14. Unexpected roles for cryptochrome 2 and phototropin revealed by high-resolution analysis of blue light-mediated hypocotyl growth inhibition. Folta, K.M., Spalding, E.P. Plant J. (2001) [Pubmed]
  15. The enhancement of phototropin-induced phototropic curvature in Arabidopsis occurs via a photoreversible phytochrome A-dependent modulation of auxin responsiveness. Stowe-Evans, E.L., Luesse, D.R., Liscum, E. Plant Physiol. (2001) [Pubmed]
  16. RPT2 is a signal transducer involved in phototropic response and stomatal opening by association with phototropin 1 in Arabidopsis thaliana. Inada, S., Ohgishi, M., Mayama, T., Okada, K., Sakai, T. Plant Cell (2004) [Pubmed]
  17. From The Cover: A role for Arabidopsis cryptochromes and COP1 in the regulation of stomatal opening. Mao, J., Zhang, Y.C., Sang, Y., Li, Q.H., Yang, H.Q. Proc. Natl. Acad. Sci. U.S.A. (2005) [Pubmed]
  18. PHYTOCHROME KINASE SUBSTRATE 1 is a phototropin 1 binding protein required for phototropism. Lariguet, P., Schepens, I., Hodgson, D., Pedmale, U.V., Trevisan, M., Kami, C., de Carbonnel, M., Alonso, J.M., Ecker, J.R., Liscum, E., Fankhauser, C. Proc. Natl. Acad. Sci. U.S.A. (2006) [Pubmed]
  19. An auxilin-like J-domain protein, JAC1, regulates phototropin-mediated chloroplast movement in Arabidopsis. Suetsugu, N., Kagawa, T., Wada, M. Plant Physiol. (2005) [Pubmed]
  20. Use of confocal laser as light source reveals stomata-autonomous function. Ca??amero, R.C., Boccalandro, H., Casal, J., Serna, L. PLoS ONE (2006) [Pubmed]
  21. Rice NPH1 homologues, OsNPH1a and OsNPH1b, are differently photoregulated. Kanegae, H., Tahir, M., Savazzini, F., Yamamoto, K., Yano, M., Sasaki, T., Kanegae, T., Wada, M., Takano, M. Plant Cell Physiol. (2000) [Pubmed]
  22. Comparative investigation of the LOV1 and LOV2 domains in Adiantum phytochrome3. Iwata, T., Nozaki, D., Tokutomi, S., Kandori, H. Biochemistry (2005) [Pubmed]
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