Identification and characterization of a Pi isoform of glutathione S-transferase (GSTP1) as a zeaxanthin-binding protein in the macula of the human eye

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Publication Type Journal Article
School or College College of Pharmacy; School of Medicine
Department Ophthalmology; Pharmacology & Toxicology; Obstetrics & Gynecology
Creator Frederick, Jeanne M.; Thulin, Craig; Bernstein, Paul S.
Other Author Bhosale, Prakash; Larson, Alexander J; Southwick, Katie
Title Identification and characterization of a Pi isoform of glutathione S-transferase (GSTP1) as a zeaxanthin-binding protein in the macula of the human eye
Date 2004
Description Uptake, metabolism, and stabilization of xanthophyll carotenoids in the retina are thought to be mediated by specific xanthophyll-binding proteins (XBPs). A membrane-associated XBP was purified from human macula using ion-exchange chromatography followed by gel-exclusion chromatography. Two-dimensional gel electrophoresis showed a prominent spot of 23 kDa and an isoelectric point of 5.7. Using mass spectral sequencing methods and the public NCBI database, it was identified as a Pi isoform of human glutathione S-transferase (GSTP1). Dietary (3R,3'R)-zeaxanthin displayed the highest affinity with an apparent Kd of 0.33 microm, followed by (3R,3'S-meso)-zeaxanthin with an apparent Kd of 0.52 microm. (3R,3'R,6'R)-Lutein did not display any high-affinity binding to GSTP1. Other human recombinant glutathione S-transferase (GST) proteins, GSTA1 and GSTM1, exhibited only low affinity binding of xanthophylls. (3R,3'S-meso)-Zeaxanthin, an optically inactive nondietary xanthophyll carotenoid present in the human macula, exhibited a strong induced CD spectrum in association with human macular XBP that was nearly identical to the CD spectrum induced by GSTP1. Like-wise, dietary (3R,3'R)-zeaxanthin displayed alterations in its CD spectrum in association with GSTP1 and XBP. Other mammalian xanthophyll carrier proteins such as tubulin, high-density lipoprotein, low-density lipoprotein, albumin, and beta-lactoglobulin did not bind zeaxanthins with high affinity, and they failed to induce or alter xanthophyll CD spectra to any significant extent. Immunocytochemistry with an antibody to GSTP1 on human macula sections showed highest labeling in the outer and inner plexiform layers. These results indicate that GSTP1 is a specific XBP in human macula that interacts with (3R,3'S-meso)-zeaxanthin and dietary (3R,3'R)-zeaxanthin in contrast to apparently weaker interactions with (3R,3'R,6'R)-lutein.
Type Text
Publisher American Society for Biochemistry and Molecular Biology (ASBMB)
Volume 279
Issue 47
First Page 49447
Last Page 49454
Subject Circular Dichroism; Isoelectric Focusing; Macula Lutea; Xanthophylls
Subject MESH Glutathione Transferase; Isoenzymes; Lutein
Language eng
Bibliographic Citation Bhosale P, Larson AJ, Frederick JM, Southwick K, Thulin CD, Bernstein PS. (2004). Identification and characterization of a Pi isoform of glutathione S-transferase (GSTP1) as a zeaxanthin-binding protein in the macula of the human eye. J Biol Chem, 279(47), 49447-54.
Rights Management (c)American Society for Biochemistry and Molecular Biology (ASBMB)
Format Medium application/pdf
Identifier ir-main,1785
ARK ark:/87278/s6db8k4j
Setname ir_uspace
Date Created 2012-06-13
Date Modified 2012-06-13
ID 703745
Reference URL https://collections.lib.utah.edu/ark:/87278/s6db8k4j
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