C-reactive protein, molecular models. Two molecules of the protein are seen. The protein is made up of five sub-units (monomers) arranged in a ring. The secondary structure of the protein is shown, with beta sheets (arrows) and alpha helices (spirals) connected by linking regions. C-reactive protein (CRP) is a blood plasma protein produced by the liver. It is an acute phase protein, one whose levels rise in response to inflammation. It assists the binding of complement proteins to foreign or damaged cells, an immunological response that destroys the target cells. High blood levels of CRP are associated with increased risk of heart disease and diabetes.