May 2008
Volume 49, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2008
A Site-Directed Spin Labeling Study of the Conformation of Free and Rhodopsin-Bound Arrestin
Author Affiliations & Notes
  • W. M. Cleghorn
    Pharmacology, Vanderbilt Univ Med Ctr, Nashville, Tennessee
  • M. Kim
    UCLA, Los Angeles, California
  • N. Van Eps
    UCLA, Los Angeles, California
  • S. A. Vishnivetskiy
    Pharmacology, Vanderbilt Univ Med Ctr, Nashville, Tennessee
  • S. M. Hanson
    Pharmacology, Vanderbilt Univ Med Ctr, Nashville, Tennessee
  • V. V. Gurevich
    Pharmacology, Vanderbilt Univ Med Ctr, Nashville, Tennessee
  • W. L. Hubbell
    UCLA, Los Angeles, California
  • Footnotes
    Commercial Relationships  W.M. Cleghorn, None; M. Kim, None; N. Van Eps, None; S.A. Vishnivetskiy, None; S.M. Hanson, None; V.V. Gurevich, None; W.L. Hubbell, None.
  • Footnotes
    Support  NIH grants EY11500, GM 77561 (VVG), EY05216 (WLH).
Investigative Ophthalmology & Visual Science May 2008, Vol.49, 161. doi:https://doi.org/
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      W. M. Cleghorn, M. Kim, N. Van Eps, S. A. Vishnivetskiy, S. M. Hanson, V. V. Gurevich, W. L. Hubbell; A Site-Directed Spin Labeling Study of the Conformation of Free and Rhodopsin-Bound Arrestin. Invest. Ophthalmol. Vis. Sci. 2008;49(13):161. doi: https://doi.org/.

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

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Abstract
 
Purpose:
 

To elucidate conformational changes in rod arrestin induced by its binding to light-activated phosphorylated rhodopsin (P-Rh*).

 
Methods:
 

Rod arrestin forms tetramers at physiological concentrations. To explore the structure of free (monomer in the solution tetramer) and rhodopsin-bound arrestin, pairs of spin labels were introduced in the molecule. Distances between the pairs were determined by DEER spectroscopy to provide global structural constraints.

 
Results:
 

We have previously shown that that the structure of the crystal and solution tetramer is different, that only monomeric arrestin binds to P-Rh*, and that arrestin binds individual rhodopsin molecules. The arrestin crystal structure reveals a tetramer in which the monomers have different conformations in flexible regions of the molecule, including the "finger loop" involved in P-Rh* binding. The set from which pairs were selected are shown in the figure, and include sites in both the N- and C-domains.

 
Conclusions:
 

Distance data are consistent with the D chain conformation seen in the crystal structure tetramer in which the finger loop is in a "bent over", rather than extended, conformation. Pairs involving residue 344 show broad distance distributions indicating plasticity of the host loop. Upon binding to P-Rh*, the pattern of observed distance changes suggests that the structure of the cores of both N- and C-domains remains essentially unchanged, but that specific rearrangements of the finger loop and an adjacent loop containing residue 139 take place.  

 
Keywords: protein structure/function • photoreceptors • signal transduction 
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