Figure 3 of Saari, Mol Vis 2009; 15:844-854.


Figure 3. 9-cis-Retinal was released from CRALBP by acidic glycerophospholipids. Cellular retinaldehyde-binding protein (CRALBP)·9-cis-retinal was incubated in the dark with NH2OH and small unilamellar vesicles (SUVs). Release of 9-cis-retinal was followed using the spectral assay (A and C) and the HPLC assay (B and D). Incubation of CRALBP·9-cis-retinal with SUVs composed of 50 mol% phosphatidylcholine (PC) and 50 mol% phosphatidic acid (PA) produced spectral changes over 18 h consistent with release of 9-cis-retinal for reaction with NH2OH (A), and high performance liquid chromatography (HPLC) analysis of an 18 h sample demonstrated recovery of 9-cis-retinal oximes (B). Incubation with SUVs composed of 100 mol% PC had little effect on the absorption spectrum of 9-cis-retinal bound to CRALBP (C), and minimal amounts of 9-cis-retinal oximes were recovered (D). The amount of 9-cis-retinal released in A was approximately 60% of the total bound to the protein. In B and D, only the oxime regions of the chromatograms are shown. The data shown in the panels are representative of at least five independent repeats of the experiment.