The multifunctional vitamin D binding protein (DBP) is an actin-sequestering protein present in blood. The crystal structure of the actin-DBP complex was determined at 2.4 A resolution. DBP binds to actin subdomains 1 and 3 and occludes the cleft at the interface between these subdomains. Most remarkably, DBP demonstrates an unusually large actin-binding interface, far exceeding the binding-interface areas reported for other actin-binding proteins such as profilin, DNase I and gelsolin. The fast-growing side of actin monomers is blocked completely through a perfect structural fit with DBP, demonstrating how DBP effectively interferes with actin-filament formation. It establishes DBP as the hitherto best actin-sequestering protein and highlights its key role in suppressing and preventing extracellular actin polymerization.
The vitamin D binding protein binds globular actin with high af®nity and is involved in the clearance of actin from the blood circulation. A complex of the human vitamin D binding protein and rabbit muscle actin was subjected to puri®cation steps. The pure complex was crystallized using the hanging-drop vapour-diffusion procedure. The best obtained crystals belong to the monoclinic space group P2 1 , with unit-cell parameters a = 74.44, b = 74.90, c = 88.02 A Ê , = 110.19 . A complete data set to 2.4 A Ê was collected from a single crystal using synchrotron radiation at DESY,
A kepi is a light military cap with a peak of leather or cloth and a chinstrap of leather or cord. The kepi originated during Algerian war in the nineteenth century but was then was named a casquette or bonnet de la police à visière. The casquette (képi) was modelled on, and developed from, a fifteenth-century bonnet with a peak and the cap called a montera or boukinkan worn during the reign of Louis XIII . In the nineteenth century, the peaked cap became pervasive as military headgear in many different forms. In the twentieth century, it has assumed many forms and uses beyond the military in a wide range of sports, professional and other civil uniforms.
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