Sandbox Reserved 779: Difference between revisions
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The lipocalin family is a large and diverse family of proteins with functions varying from insect camouflage to small hydrophobic molecule transport typified by the serum retinol-binding protein <ref>http://www.biochemj.org/bj/318/bj3180001.htm</ref> The crystal structures so far determined reveal the typical lipocalin to be an eight-stranded antiparallel β-barrel arranged to form a conical central calyx or cavity in which the hydrophobic ligand is located.<ref>PMID:6540172</ref> | The lipocalin family is a large and diverse family of proteins with functions varying from insect camouflage to small hydrophobic molecule transport typified by the serum retinol-binding protein <ref>http://www.biochemj.org/bj/318/bj3180001.htm</ref> The crystal structures so far determined reveal the typical lipocalin to be an eight-stranded antiparallel β-barrel arranged to form a conical central calyx or cavity in which the hydrophobic ligand is located.<ref>PMID:6540172</ref> | ||
===Biological Function=== | ===Biological Function=== | ||
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the transport of retinol and/or fatty acids [8,50]. It binds retinol with a higher affinity than does RBP [51] and, as with RBP, specific binding of retinol to β-Lg has been observed in the small intestine of the neonatal calf [3]. The structure of RBP with retinol bound within the hydrophobic calyx has been solved [2] and retinol was successfully modelled into our previous β-Lg structure [3]. β-Lg contains two tryptophans, Trp19 and Trp61, and their fluorescence is altered when retinol is bound [51].<ref>PMID:9115437</ref> | the transport of retinol and/or fatty acids [8,50]. It binds retinol with a higher affinity than does RBP [51] and, as with RBP, specific binding of retinol to β-Lg has been observed in the small intestine of the neonatal calf [3]. The structure of RBP with retinol bound within the hydrophobic calyx has been solved [2] and retinol was successfully modelled into our previous β-Lg structure [3]. β-Lg contains two tryptophans, Trp19 and Trp61, and their fluorescence is altered when retinol is bound [51].<ref>PMID:9115437</ref> | ||
Co-crystallized β-Lg with palmitic acid, and the refined structure (R = 0.204, R free = 0.240 for 6,888 reflections to 2.5-Å resolution) reveals that the ligand binds in the central cavity in a manner similar to the binding of retinol to the related lipocalin, serum retinol-binding protein. The carboxyl group binds to both Lys-60 and Lys-69 at the entrance to the cavity. The hydrophobic tail stretches in an almost fully extended conformation into the center of the protein. | Co-crystallized β-Lg with palmitic acid, and the refined structure (R = 0.204, R free = 0.240 for 6,888 reflections to 2.5-Å resolution) reveals that the ligand binds in the central cavity in a manner similar to the binding of retinol to the related lipocalin, serum retinol-binding protein. The carboxyl group binds to both Lys-60 and Lys-69 at the entrance to the cavity. The hydrophobic tail stretches in an almost fully extended conformation into the center of the protein.<ref>PMID:9867826</ref> | ||
