HY4 gene of A. thaliana encodes a protein with characteristics of a blue-light photoreceptor

Nature. 1993 Nov 11;366(6451):162-6. doi: 10.1038/366162a0.


Specific responses to blue light are found throughout the biological kingdom. These responses--which in higher plants include phototropism, inhibition of hypocotyl elongation, and stomatal opening--are in many cases thought to be mediated by flavin-type photoreceptors. But no such blue-light photoreceptor has yet been identified or isolated, although blue-light responses in plants were reported by Darwin over a century ago, long before the discovery of the now relatively well characterized red/far-red light photoreceptor, phytochrome. Here we describe the isolation of a gene corresponding to the HY4 locus of Arabidopsis thaliana. The hy4 mutant is one of several mutants that are selectively insensitive to blue light during the blue-light-dependent inhibition of hypocotyl elongation response, which suggests that they lack an essential component of the cryptochrome-associated light-sensing pathway. The HY4 gene, isolated by gene tagging, was shown to encode a protein with significant homology to microbial DNA photolyases. As photolyases are a rare class of flavoprotein that catalyse blue-light-dependent reactions, the protein encoded by HY4 has a structure consistent with that of a flavin-type blue-light photoreceptor.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Arabidopsis
  • Arabidopsis Proteins
  • Base Sequence
  • Cryptochromes
  • Deoxyribodipyrimidine Photo-Lyase / genetics
  • Drosophila Proteins*
  • Eye Proteins*
  • Flavoproteins*
  • Genes, Plant
  • Light*
  • Molecular Sequence Data
  • Mutation
  • Photoreceptor Cells*
  • Photoreceptor Cells, Invertebrate*
  • Plant Proteins / genetics*
  • Receptors, G-Protein-Coupled
  • Sequence Homology, Amino Acid


  • Arabidopsis Proteins
  • CRY1 protein, Arabidopsis
  • Cryptochromes
  • Drosophila Proteins
  • Eye Proteins
  • Flavoproteins
  • Plant Proteins
  • Receptors, G-Protein-Coupled
  • cry protein, Drosophila
  • Deoxyribodipyrimidine Photo-Lyase