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All three human scavenger receptor class B proteins can bind and transport all three macular xanthophyll carotenoids
Journal article   Peer reviewed

All three human scavenger receptor class B proteins can bind and transport all three macular xanthophyll carotenoids

Rajalekshmy Shyam, Preejith Vachali, Aruna Gorusupudi, Kelly Nelson and Paul S. Bernstein
Archives of biochemistry and biophysics, Vol.634, pp.21-28
11/15/2017
DOI: 10.1016/j.abb.2017.09.013
PMCID: PMC5698089
PMID: 28947101
url
https://www.ncbi.nlm.nih.gov/pmc/articles/5698089View
Open Access

Abstract

Carotenoids are plant pigment molecules that are potent antioxidants. Carotenoids cannot be synthesized de novo; therefore, their dietary intake and transport to various tissues are essential to harness their health benefits. Two of the three scavenger receptor class B (SRB) proteins, SR-B1 and CD36, have been implicated as carotenoid transporters in lower species and in various tissues of higher animals. The function of the third SRB protein, SR-B2, in carotenoid transport is unknown. Using surface plasmon resonance (SPR) analyses, we have determined that all three human SRB proteins are capable of binding the macular xanthophyll carotenoids; lutein, zeaxanthin, and meso-zeaxanthin. By over-expressing human SRB proteins in cells that do not endogenously express SRBs, we have determined that lutein uptake is enhanced in the presence of LDL and is mediated by SR-B1 and CD36. SR-B1, SR-B2, and CD36 were able to take up significant amounts of zeaxanthin as well as meso-zeaxanthin, and uptake was increased in the presence of HDL. Our analyses revealed no apparent differences in protein expression profiles of SRBs in central and peripheral regions of human donor tissues, indicating that carotenoid-binding proteins rather than transporters are likely to mediate selective accumulation of carotenoids into the macula. •All three SRB proteins are capable of binding macular carotenoids.•Over-expressed SRB proteins can transport macular carotenoids.•LDL enhances lutein uptake, HDL increases zeaxanthin and meso-zeaxanthin uptake.•All three SRB proteins are expressed in the primate eye.
 Eye HDL LDL Lipoproteins Lutein Macula meso-Zeaxanthin Retina RPE Scavenger receptors Zeaxanthin

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