Year-end Sale % OFF 
Abstract
Photoreceptor guanylyl cyclase (ROS-GC), converting GTP into cGMP and pyrophosphate, is a key enzyme in the regulation of the visual transduction cascade. ROS-GC requires GC-activating proteins (GCAPs) and low free [Ca] for full activity. We found that when choline or potassium were the major cations present, light caused a 70% inhibition of stimulated ROS-GC in native unstripped membranes. In the presence of sodium ions, however, no inhibition was observed. ROS-GC activity of ROS membranes, stripped of transducin and other components, was not affected by light when reconstituted with GCAP1 only. However, when stripped ROS membranes were reconstituted with both GCAP1 and either transducin (T alpha beta gamma) or the T beta gamma-subunits, the inhibition of ROS-GC by light was restored. The T alpha-subunit alone was ineffective. These results suggest that under saturating light conditions, ROS-GC may be regulated by T beta gamma and cations, providing a possible mechanism of desensitization and light adaptation.
Submitted Version
Published Version
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.
