May 2006
Volume 47, Issue 13
ARVO Annual Meeting Abstract  |   May 2006
Selective GCAP1 Binding Site in ROS–GC1
Author Affiliations & Notes
  • R.K. Sharma
    UMD New Jersey, Stratford, NJ
    Professor Dept of Cell Biology,
  • K.W. Koch
    AG Biochemistry,, Carl von Ossietzky University, Oldenburg, Germany
  • C. Lange
    Institute of Biotechnology, Martin–Luther University, Halle, Germany
  • T. Duda
    UMD New Jersey, Stratford, NJ
    Cell Biology,
  • Footnotes
    Commercial Relationships  R.K. Sharma, None; K.W. Koch, None; C. Lange, None; T. Duda, None.
  • Footnotes
    Support  NIH Grant DC005349 and HL070015; DGF KO948/5–3
Investigative Ophthalmology & Visual Science May 2006, Vol.47, 804. doi:
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    • Get Citation

      R.K. Sharma, K.W. Koch, C. Lange, T. Duda; Selective GCAP1 Binding Site in ROS–GC1 . Invest. Ophthalmol. Vis. Sci. 2006;47(13):804.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose: : ROS–GC1 is a photoreceptor membrane guanylate cyclase, which through two Ca2+ sensor proteins, GCAP1 and GCAP2, controls phototransduction. GCAP1 and GCAP2 modulated domains in ROS–GC1 are distinct. In this investigation the biochemical perimeters of the GCAP1–modulated site have been defined.

Methods: : Mutagenesis/expression/reconstitution experiments, peptide competition, real–time binding (surface plasmon resonance spectroscopy) experiments, co–immunoprecipitation and cross–linking studies were carried out.

Results: : Deletion and point mutation/expression studies have identified two GCAP1 regulatory sites within the juxtamembrane portion of the kinase homology domain of ROS–GC1, M445–L456 and L503–I522. Co–immunoprecipitation and SPR experiments show that the ROS–GC1 soluble fragment aa S470 to A653 directly binds GCAP1 (KD value of 0.25 µM as determined by SPR) but not GCAP2. The binding occurs in the presence and absence of Ca2+ with comparable KD values. Although both peptides, M445–L456 and L503–I522, inhibit GCAP1–dependent ROS–GC1 activity only the L503–I522 peptide binds GCAP1.

Conclusions: : The ROS–GC1–GCAP1 signaling pathway operates via a specific site on ROS–GC1; the site is distinct from the GCAP2–modulatory site, and is Ca2+–independent.

Keywords: calcium • photoreceptors • signal transduction 

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