Abstract
The NPH1 gene of Arabidopsis thaliana encodes a 120-kilodalton serine-threonine protein kinase hypothesized to function as a photoreceptor for phototropism. When expressed in insect cells, the NPH1 protein is phosphorylated in response to blue light irradiation. The biochemical and photochemical properties of the photosensitive protein reflect those of the native protein in microsomal membranes. Recombinant NPH1 noncovalently binds flavin mononucleotide, a likely chromophore for light-dependent autophosphorylation. The fluorescence excitation spectrum of the recombinant protein is similar to the action spectrum for phototropism, consistent with the conclusion that NPH1 is an autophosphorylating flavoprotein photoreceptor mediating phototropic responses in higher plants.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Animals
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Arabidopsis / genetics
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Arabidopsis / physiology*
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Arabidopsis Proteins*
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Cell Line
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Cryptochromes
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Drosophila Proteins*
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Eye Proteins*
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Flavin Mononucleotide / metabolism
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Flavoproteins / physiology
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Genes, Plant
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Light
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Mutation
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Phosphoproteins / genetics
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Phosphoproteins / metabolism*
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Phosphorylation
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Photoreceptor Cells, Invertebrate*
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Phototropism*
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Protein Serine-Threonine Kinases / genetics
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Protein Serine-Threonine Kinases / metabolism*
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Receptors, G-Protein-Coupled
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Recombinant Proteins / metabolism
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Spectrometry, Fluorescence
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Spodoptera
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Transfection
Substances
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Arabidopsis Proteins
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CRY1 protein, Arabidopsis
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Cryptochromes
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Drosophila Proteins
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Eye Proteins
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Flavoproteins
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Phosphoproteins
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Receptors, G-Protein-Coupled
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Recombinant Proteins
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cry protein, Drosophila
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Flavin Mononucleotide
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NPH1 protein, Arabidopsis
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Protein Serine-Threonine Kinases