Sandbox Reserved 1121

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This Sandbox is Reserved from 15/12/2015, through 15/06/2016 for use in the course "Structural Biology" taught by Bruno Kieffer at the University of Strasbourg, ESBS. This reservation includes Sandbox Reserved 1120 through Sandbox Reserved 1159.

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Human C-reactive protein complexed with phosphocholine

spinqualitylabelsall models Caption for this structure Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D This is a default text for your page '. Click above on edit this page' to modify. Be careful with the < and > signs. You may include any references to papers as in: the use of JSmol in Proteopedia or to the article describing Jmol to the rescue. The C-reactive protein has been given this name because it precipitates the C polysaccharide in the cell wall. Structure CRP structure Ser53, His95, Cys97, Asp112, Gly113, Gly136, Gly154, Val165, Leu166, Ile171, and Gly196 are the highly conserved residues in the primary sequence of CRP. The C-reactive protein is a homopentamer of non-covalently bound subunits. Each subunit is a 25 Da protein consisting of 224 residues bound together. The secondary structure is formed of one α-helix and two antiparallel β-sheets. The predominant structure is β-sheet but short helical regions can be noticed for the residues 43 and 185. The residues Glu197 and Lys123 of CRP form an intermolecular ion pair. The diameterof the CRP pentamer is 102 Å, the inner pore diameter is 30 Å and the diameter of a subunit is 36 Å. Ca2+ binding-site CRP is a calcium dependent structure. Effectively, Ca2+ is required for PC binding, and more precisely for the formation of the PC binding site thanks to structural rearrangements. The protection against denaturation and proteolysis is performed through Ca2+ binding too. In the absence of Ca2+, hCRP is cleaved between Asn145 and Phe146 by nagarse protease, and between Phe146 and Glu147 by pronase. Asp60, Asn61, Glu138, Asp140 and the main-chain carbonyl of Gln139 residues allow the first calcium ion binding, and the second is performed through Glu138, Asp140, Glu147 and Gln150. The two Ca2+-binding sites are overlapping in a loop. In the absence of Ca2+, the loop changes conformaion and releases the proteolysis site. Therefore Ca2+ protects CRP form proteolytic cleavage. PC binding site PC stands for phosphocholine. It is a phospholipid in cell membranes and a plasma lipoproteins. Phe-66 and Glu-81 are the two key residues that enable the binding of PC. They interact with the choline function of PC, which therefore lies inside the PC-binding site. CRP binds the phosphocholine and other ligands in a Ca2+-dependent way. The PC-binding site is next to the Ca2+-binding sites on the same face of the CRP protein. The PC-binding site is a hydrophobic pocket constituted by the residues Leu64, Phe66, Thr76 and the two Ca2+. The phosphate groupe of PC interacts by coordination with the two Ca2+. CRP can also bind chromatin, histones, small nuclear robonucleoproteins nuclear envelop proteins and nucleosomes Ca2+-dependently. Function CRP binds to PC located on the surface of bacteria that infected the organism. The resulting immune response is the phygocytosis of PC-expressing bacteria. The CRP is therefore part of the acute phase response which is a rapid concentration variation of plasma proteins . Biomedical interest Healthy humans have a CRP rate which is generally about 1 μg/mL. CRP is secreted by the liver into the blood circulation. CRP level is 1000 times higher in a cytokine-mediated response due to tissue injury, infection and inflammation. Therefore the CRP rate in serum is common use to detect the activity of a disease. CRP can be defined as a target for the development of cardioprotection and neuroprotection. Structural highlights This is a sample scene created with SAT to color by Group, and another to make a transparent representation of the protein. You can make your own scenes on SAT starting from scratch or loading and editing one of these sample scenes.