Abstract
G-protein-coupled receptors are membrane proteins that are regulated by a small family of arrestin proteins. During formation of the arrestin–receptor complex, arrestin first interacts with the phosphorylated receptor C terminus in a pre-complex, which activates arrestin for tight receptor binding. Currently, little is known about the structure of the pre-complex and its transition to a high-affinity complex. Here we present molecular dynamics simulations and site-directed fluorescence experiments on arrestin-1 interactions with rhodopsin, showing that loops within the C-edge of arrestin function as a membrane anchor. Activation of arrestin by receptor-attached phosphates is necessary for C-edge engagement of the membrane, and we show that these interactions are distinct in the pre-complex and high-affinity complex in regard to their conformation and orientation. Our results expand current knowledge of C-edge structure and further illuminate the conformational transitions that occur in arrestin along the pathway to tight receptor binding.
Highlights
G-protein-coupled receptors are membrane proteins that are regulated by a small family of arrestin proteins
The conformational stability of the simulated isolated C-domain was steady during all simulation runs with an average RMSD that did not exceed 1.7 Å compared with the crystallized C-domain of full-length arrestin (Supplementary Table 1)
We investigated how the C-domain of p44 might interact with the membrane using unbiased molecular dynamics simulations (10 replicates of 100 ns, Table 1, MD3)
Summary
G-protein-coupled receptors are membrane proteins that are regulated by a small family of arrestin proteins. The phosphorylated receptor C terminus displaces the arrestin C-tail, which results in an B21° rotation of the N- and C-domains against each other and an increase in flexibility in receptorbinding loops in the central crest region (see Fig. 1a)[9,10,11] These conformational changes facilitate tight binding and transition to the high-affinity complex (Fig. 1c). A stable complex was achieved by introducing activating mutations into both binding partners, mouse arrestin-1 and human opsin, and fusing the N terminus of arrestin to the C terminus of the receptor via a flexible linker Despite these modifications and the lack of receptor phosphorylation, this structure indicates how the conformational changes associated with arrestin activation facilitate coupling to the active receptor. The interaction of the 344-loop with the membrane was proposed by our group based on site-directed fluorescence experiments[14]
Sign-in/Register to view highlights & summary 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.
