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Teresa Duda, Alexandre Pertzev, Rameshwar K. Sharma; Signature Phototransduction Switch in ROS-GC1. Invest. Ophthalmol. Vis. Sci. 2011;52(14):1182. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To explain on structural basis the phototransduction linked principles of ROS-GC1.
Mutational analysis, living cell fluorescence, surface plasman reasonance (SPR) spectroscopy, co-immunoprecipitation and standard biochemical techniques.
A Ca2+ sensing phototransduction linked membrane guanylate cyclase ROS-GC1 switching motif has been identified. The intriguing part of this motif is that it is regulated both by GCAP1 and GCAP2, despite the facts that the target modules of these GCAPs reside on opposite sides of the core catalytic site of ROS-GC1. This motif is composed of seven residues, 657WTAPELL663. In situ living cell fluorescence, coimmunoprecipitation and SPR studies demonstrate that this motif does not bind GCAPs. The deletion and enzymatic analyses show that it also is not involved in the regulation of the basal catalytic activity. Its function is to transduce the Ca2+-modulated GCAP1 and GCAP2 signals of ROS-GC1 activation. In keeping with this concept, transformation of the motif to 657AAAAAAA663 results in the almost total loss of the Ca2+-sensing ROS-GC1 activity. An important functional residue in the motif is 657W because its introduction in the 7A mutant restores about 65% of ROS-GC1 Ca2+ modulated activity, the remainder 35% appears to be dependent on the remainder or the intact motif.
A remarkable Ca2+ modulated signal transduction mechanism exists in ROS-GC1. This mechanism may explain the common means by which ROS-GC1 senses and processes the LIGHT signals of varying luminosity.
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