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Mutations in arrestin alpha‐helix I affect receptor binding
Author(s) -
Gurevich Vsevolod V,
Vishnivetskiy Sergey A,
Francis Derek J,
Hanson Susan M,
Van Eps Ned,
Hubbell Wayne L,
Klug Candice S
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.1046.6
Subject(s) - arrestin , rhodopsin , helix (gastropod) , receptor , chemistry , biophysics , crystallography , g protein coupled receptor , biology , biochemistry , retinal , ecology , snail
Receptor‐binding elements of arrestin proteins were mapped to the concave surfaces of the two arrestin domains using a variety of methods. Therefore, it is generally believed that in the arrestin‐receptor complex these concave sides of the two arrestin domains face the plane of the membrane. We found that mutations in alpha‐helix I, localized on the side of the arrestin N‐domain opposite to the concave surface, significantly reduce visual arrestin binding to phosphorylated light‐activated rhodopsin and the stability of the arrestin‐rhodopsin complex. The analysis of accessibility of spin labels introduced in the helix to hydrophilic and hydrophobic reagents shows that the helix remains in a hydrophilic environment in receptor‐bound arrestin. Distance measurements by EPR in doubly spin labeled arrestin show that in the receptor‐bound and free arrestin states the position of the helix remains essentially the same. Our recent finding that each receptor molecule binds its own arrestin excludes the possibility that the concave sides of the two domains and the helix interact with two different receptor molecules. We propose two models of the arrestin‐receptor complex consistent with the role of alpha‐helix I in the interaction. NIH grants EY11500, GM 77561 (VVG), EY05216 (WLH), AI58024, GM70642 (CSK).