Sandbox Reserved 821: Difference between revisions
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= Human C-reactive protein (CRP) = | = Human C-reactive protein (CRP) = | ||
The C-reactive protein (CRP) is a plasma protein, mainly synthesized by the liver. Its concentration may increase rapidly, as much as 1000-fold or more, in response to tissue injury, infection and inflammation: It's an acute-phase protein. | =<ref>PMID:10368284</ref> <ref>PMID:15337754</ref> The C-reactive protein (CRP) is a plasma protein, mainly synthesized by the liver. Its concentration may increase rapidly, as much as 1000-fold or more, in response to tissue injury, infection and inflammation: It's an acute-phase protein. | ||
CRP binds to phosphocholine which is exposed on died or dying cells and expressed on the surfaces of pathogens. Then, it may activate the complement system via interaction with C1q, and enhance phagocytosis by macrophages via its binding to Fcγ receptors. In addition to the fact that this protein has been highly conserved during evolution, this suggests that CRP is a very important part of the innate immune response, in the host defense. | CRP binds to phosphocholine which is exposed on died or dying cells and expressed on the surfaces of pathogens. Then, it may activate the complement system via interaction with C1q, and enhance phagocytosis by macrophages via its binding to Fcγ receptors. In addition to the fact that this protein has been highly conserved during evolution, this suggests that CRP is a very important part of the innate immune response, in the host defense. | ||
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== '''Structure of CRP''' == | == '''Structure of CRP''' == | ||
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Each protomer has a recognition face (also called face B) with a phosphocholine binding site (carrying two calcium ions), made of a two-layered β sheet. The other face - the effector face (or face A) - where complement C1q and Fc receptors bind, contains a single α helix. Consequently, the pentamer consists of five α helices on one side, and ten calcium ions on the other. | Each protomer has a recognition face (also called face B) with a phosphocholine binding site (carrying two calcium ions), made of a two-layered β sheet. The other face - the effector face (or face A) - where complement C1q and Fc receptors bind, contains a single α helix. Consequently, the pentamer consists of five α helices on one side, and ten calcium ions on the other. | ||
== '''The Calcium and Phosphocholine binding sites''' === | == '''The Calcium and Phosphocholine binding sites''' === | ||
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==='''''Calcium'''''=== | ==='''''Calcium'''''=== | ||
There are two <scene name='56/568019/Structure_of_crp_v2/1'>calcium-binding sites</scene> per CRP protomer. | There are two <scene name='56/568019/Structure_of_crp_v2/1'>calcium-binding sites</scene> per CRP protomer. | ||
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==='''''Phosphocholine'''''=== | ==='''''Phosphocholine'''''=== | ||
Phosphocholine is an universal phospholipid found particularly in the cell membranes and plasma lipoproteins of bacteria, fungi, plants and other eukaryotic organisms whose us, the human beings. However, CRP can only bind phosphocholine of our damaged or apoptotic cells, as head groups of phosphocholine are inaccessible to CRP in “normal” cells. | Phosphocholine is an universal phospholipid found particularly in the cell membranes and plasma lipoproteins of bacteria, fungi, plants and other eukaryotic organisms whose us, the human beings. However, CRP can only bind phosphocholine of our damaged or apoptotic cells, as head groups of phosphocholine are inaccessible to CRP in “normal” cells. | ||
