Abstract
In photoreceptor cells cGMP is the second messenger that transduces light into an electrical response. Regulation of cGMP synthesis by Ca2+ is one of the key mechanisms by which Ca2+ exerts negative feedback to the phototransduction cascade in the process of light adaptation. This Ca2+ feedback to retinal guanylyl cyclases (Ret-GCs) is conferred by the guanylate cyclase-activating proteins (GCAPs). Mutations in GCAP1 that disrupt the Ca2+ regulation of Ret-GCs in vitro have been associated with severe human vision disorders. This chapter focuses on recent data obtained from biochemical and electrophysiological studies of GCAP1/GCAP2 knockout mice and other GCAP transgenic mice, addressing: 1. the quantitative aspects of the Ca2+-feedback to Ret-GCs in regulating the light sensitivity and adaptation in intact rods; 2. functional differences between GCAP1 and GCAP2 in intact rod photoreceptors; and 3. whether GCAP mutants with impaired Ca2+ binding lead to retinal disease in vivo by constitutive activation of Ret-GCs and elevation of intracellular cGMP, as predicted from in vitro studies.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
