C-reactive protein

C-reactive protein is an acute phase protein produced by the liver within 6 hours of an acute inflammatory stimulus. Levels peak after about 50 hours.

CRP is a pentraxin protein that exhibits calcium dependant ligand binding and a distinctive flattened β-jellyroll structure. (left - image - click to enlarge) CRP is so-named because it reacts with the somatic C polysaccharide of the bacterium Streptococcus pneumoniae. Serum amyloid P component is another pentraxin, acute phase protein.

CRP binds specifically to phosphocholine moieties, conferring a host-defensive role on CRP since phosphocholine is a component of microbial polysaccharides. CRP also binds to ligands exposed on damaged cells.

CRP-phosphocholine-binding:
● activates the classical complement pathway
● acts as an opsonin ligand for phagocytosis
● neutralizes the pro-inflammatory platelet-activating factor (PAF)
● down-regulates polymorphs
CRP
● increases production of tissue-factors by monocytes
● activates smooth muscle K+ ion channels (vasodilator)
● delays apoptosis of neutrophils when the pentameric structure is lost and the molecule exists as a monomer (mCRP)

CRP is mildly elevated in: systemic lupus erythematosus, systemic sclerosis, sermatomyositis, ulcerative colitis, leukaemia, and graft-versus-host disease (GVHD).

The C-reactive protein medical test measures levels of CRP to assess acute inflammation. An association has been demonstrated between sudden cardiac death, peripheral arterial disease and hs-CRP, so serum CRP levels may correlate with cardiovascular disease risk.

tags [Proteins] [C-reactive protein] [acute phase] [classical complement pathway] [inflammation] [pentraxin]