Kinetic analysis of the activation of photoactivated adenylyl cyclase (PAC), a blue-light receptor for photomovements of Euglena Kinetic analysis of the activation of photoactivated adenylyl cyclase (PAC), a blue-light receptor for photomovements of Euglena

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抄録

Photoactivated adenylyl cyclase (PAC) was first purified from a photosensing organelle (the paraflagellar body) of the unicellular flagellate Euglena gracilis, and is regarded as the photoreceptor for the step-up photophobic response. Here, we report the kinetic properties of photoactivation of PAC and a change in intracellular cAMP levels upon blue light irradiation. Activation of PAC was dependent both on photon fluence rate and duration of irradiation, between which reciprocity held well in the range of 2-50 μmol m-2 s-1 (total fluence of 1200 μmol m-2). Intermittent irradiation also caused activation of PAC in a photon fluence-dependent manner irrespective of cycle periods. Wavelength dependency of PAC activation showed prominent peaks in the UV-B/C, UV-A and blue regions of the spectrum. The time course of the changes in intracellular cAMP levels corresponded well with that of the step-up photophobic response. From this and the kinetic properties of PAC photoactivation, we concluded that an increase in intracellular cAMP levels evoked by photoactivation of PAC is a key event of the step-up photophobic response.

収録刊行物

  • Photochemical and Photobiological Sciences = Photochemical and Photobiological Sciences

    Photochemical and Photobiological Sciences = Photochemical and Photobiological Sciences 4(9), 727-731, 2005-09

    Royal Society of Chemistry

各種コード

  • NII論文ID(NAID)
    120006576052
  • 本文言語コード
    ENG
  • 資料種別
    journal article
  • ISSN
    1474-905X
  • データ提供元
    IR 
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