Title
Identification of Apolipoprotein A-1 as a Retinoic Acid Binding Protein in the Eye
Author
Jody A. Summers, Angelica R. Harper, Christa L Feasley, Hanke Van-Der-Wel, Jennifer N. Byrum, Marcela Hermann, Christopher M. West
Year
2016
Journal
The Journal of Biological Chemistry
Abstract
All-trans-retinoic acid may be an important molecular signal in the postnatal control of eye size. The goal of this study was to identify retinoic acid binding proteins secreted by the choroid and sclera during visually guided ocular growth. Following photoaffinity labeling with all-trans-[11,12-3H] retinoic acid, the most abundant labeled protein detected in the conditioned media of choroid or sclera had an apparent Mr of 27,000 Da. Following purification and mass spectrometry, the Mr 27,000 band was identified as apolipoprotein A-1. Affinity capture of the radioactive Mr 27,000 band by anti-chick apolipoprotein A-1 antibodies confirmed its identity as apolipoprotein A-1. Photoaffinity labeling and fluorescence quenching experiments demonstrated that binding of retinoic acid to apolipoprotein A-1 is 1) concentration dependent, 2) selective for all-transretinoic acid, and 3) requires the presence of apolipoprotein A-1 associated lipids for retinoid binding. Expression of apolipoprotein A-1 mRNA and protein synthesis were markedly upregulated in choroids of chick eyes during the recovery from induced myopia, and apolipoprotein A-1 mRNA was significantly increased by retinoic acid treatment. Together, these data suggest that apolipoprotein A-1 may participate in a regulatory feedback mechanism with retinoic acid to control the action of retinoic acid on ocular targets during postnatal ocular growth.
Instrument
J-715
Keywords
Circular dichroism, Secondary structure, Ligand binding, Vesicle interactions, Tertiary structure, Biochemistry