June 2020
Volume 61, Issue 7
Free
ARVO Annual Meeting Abstract  |   June 2020
The role of the finger loop in rhodopsin binding by arrestin-1
Author Affiliations & Notes
  • Elizabeth Huh
    Vanderbilt University, Nashville, Tennessee, United States
  • Sergey A Vishnivetskiy
    Vanderbilt University, Nashville, Tennessee, United States
  • Vsevolod V Gurevich
    Vanderbilt University, Nashville, Tennessee, United States
  • Footnotes
    Commercial Relationships   Elizabeth Huh, None; Sergey Vishnivetskiy, None; Vsevolod Gurevich, None
  • Footnotes
    Support  NIH grant EY011500
Investigative Ophthalmology & Visual Science June 2020, Vol.61, 1522. doi:
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    • Get Citation

      Elizabeth Huh, Sergey A Vishnivetskiy, Vsevolod V Gurevich; The role of the finger loop in rhodopsin binding by arrestin-1. Invest. Ophthalmol. Vis. Sci. 2020;61(7):1522.

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

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Abstract

Purpose : Determine the role of individual residues in the arrestin finger loop in rhodopsin binding.

Methods : Point mutations of individual residues in bovine arrestin-1 were introduced on the background of wild type arrestin-1 and its "enhanced" phosphorylation-independent truncated (1-378) mutant. Functional effects of these mutations were tested in direct binding assay using radiolabeled proteins produced in cell-free translation.

Results : The majority of mutations cause moderate reduction of the binding to activated phophorylated rhodopsin (P-Rh*), which are less than 25%. Only mutations of Arg66, Arg81, and the deletion of Gly76 had greater negative effect. Apparently, unperturbed arrestin-1 interactions with the rhodopsin-attached phosphates prevented greater loss of binding. In contrast, virtually all mutations reduced to a much greater extent the binding of enhanced (1-378) mutant to unphosphorylated activated rhodopsin (Rh*) (this mutant demonstrates high binding to this form of rhodopsin). Some mutations (the deletions of Gly76 and Gly68) caused the loss of up to 90% of Rh* binding. Thus, the finger loop binds unphosphorylated rhodopsin elements, so that the effects of mutations are greater when the interactions with the phosphates on rhodopsin cannot compensate.

Conclusions : In the structure of the arrestin-rhodopsin complex, the finger loop of arrestin-1 inserts itself into the cavity between transmembrane helices that opens upon rhodopsin activation. The structure suggests that the finger loop serves as the "activation sensor" of arrestin-1. In agreement with this hypothesis, finger loop mutations affect arrestin-1 interactions with Rh* much more dramatically than its binding to P-Rh*.

This is a 2020 ARVO Annual Meeting abstract.

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