Structural properties of arrestin studied by chemical modification and circular dichroism
- 28 April 1992
- journal article
- research article
- Published by American Chemical Society (ACS) in Biochemistry
- Vol. 31 (16) , 3902-3906
- https://doi.org/10.1021/bi00131a003
Abstract
A unique conformation of arrestin is crucial for its interaction with phosphorylated photolyzed rhodopsin. Conformational changes in arrestin were investigated using chemical modification and circular dichroism. We studied the kinetics of sulfhydryl modification of bovine arrestin in order to determine whether its conformation is altered by the presence of ligands or salts at different ionic strengths. We found that all three cysteines (stoichiometry was 2.7 +/- 0.06 3-carboxy-4-nitrophenyl sulfide (NbS)/arrestin) are accessible for modification by NbS2. Under pseudo-first-order conditions (30-100-fold excess of NbS2 over arrestin), the modifications of the 3 cysteines are indistinguishable. At higher concentrations of NbS2 (150-300-fold excess), the pseudo-first-order plot is not linear, and the reaction can be resolved into two processes that involve two classes of sulfhydryl groups. Addition of CaCl2, MgCl2, inorganic phosphate, MgATP, or MgGTP had little effect on the rate of modification of the cysteine residues; however, heparin and inositol hexakisphosphate, which have been shown to induce conformational changes in arrestin, block modification of one sulfhydryl group of arrestin and accelerate the modification of the remaining two. Analysis of CD spectra revealed that arrestin has virtually no alpha-helical structure, about 40% beta-structure, about 18% beta-turns, and about 40% other structure. The CD spectrum for arrestin did not change in the presence of heparin. These studies suggest that arrestin exists in equilibrium between two or more conformational states. However, it is proposed that conversion between these conformations occur without altering significantly the secondary structure of arrestin.Keywords
This publication has 22 references indexed in Scilit:
- The influence of arrestin (48K protein) and rhodopsin kinase on visual transductionNeuron, 1992
- Binding of inositol phosphates to arrestinFEBS Letters, 1991
- Photoreceptor rod outer segment 48-kDa protein has ATPase activityVisual Neuroscience, 1990
- β-Arrestin: a Protein that Regulates β-adrenergic Receptor FunctionScience, 1990
- Arrestin of bovine photoreceptors reveals strong ATP bindingFEBS Letters, 1989
- Kinetics, binding constant, and activation energy of the 48-kDa protein-rhodopsin complex by extra-metarhodopsin IIBiochemistry, 1989
- Inactivation of photoexcited rhodopsin in retinal rods: the roles of rhodopsin kinase and 48-kDa protein (arrestin)Biochemistry, 1988
- Cyclic GMP Cascade of VisionAnnual Review of Neuroscience, 1986
- Light-induced binding of guanosinetriphosphatase to bovine photoreceptor membranes: effect of limited proteolysis of the membranesBiochemistry, 1981
- Information content in the circular dichroism of proteinsBiochemistry, 1981