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Structure of human amniotic fluid RBP4 saturated with laurate
Structural highlights
DiseaseRET4_HUMAN Defects in RBP4 are a cause of retinol-binding protein deficiency (RBP deficiency) [MIM:180250. This condition causes night vision problems. It produces a typical 'fundus xerophthalmicus', featuring a progressed atrophy of the retinal pigment epithelium. FunctionRET4_HUMAN Delivers retinol from the liver stores to the peripheral tissues. In plasma, the RBP-retinol complex interacts with transthyretin, this prevents its loss by filtration through the kidney glomeruli. Publication Abstract from PubMedRBP4 (plasma retinol-binding protein) is the 21kDa transporter of all-trans retinol that circulates in plasma as a moderately tight 1:1 molar complex of the vitamin with the protein. RBP4 is primarily synthesized in the liver but is also produced by adipose tissue and circulates bound to a larger protein, transthyretin, TTR, that serves to increase its molecular mass and thus avoid its elimination by glomerular filtration. This paper reports the high resolution three-dimensional structures of human RBP4 naturally lacking bound retinol purified from plasma, urine and amniotic fluid. In all these crystals we found a fatty acid molecule bound in the hydrophobic ligand-binding site, a result confirmed by mass spectrometry measurements. In addition we also report the 1.5A resolution structures of human holo-RBP4 and of the protein saturated with palmitic and lauric acid and discuss the interaction of the fatty acids and retinol with the protein. Human plasma retinol-binding protein (RBP4) is also a fatty acid-binding protein.,Perduca M, Nicolis S, Mannucci B, Galliano M, Monaco HL Biochim Biophys Acta. 2018 Apr;1863(4):458-466. doi:, 10.1016/j.bbalip.2018.01.010. PMID:29414511[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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