C-Reactive Protein (CRP) is a member of the pentraxin family of proteins, characterized by a cyclic pentameric structure. It plays a crucial role in the body’s immune response by binding to phosphocholine expressed on the surface of dead or dying cells and some types of bacteria, thereby activating the complement system . CRP is an acute-phase protein, meaning its levels in the blood increase in response to inflammation.
The rat CRP gene encodes a 230 amino acid precursor with a signal peptide of 19 amino acids and a mature polypeptide of 211 amino acids . Unlike human, mouse, and rabbit CRP, which are non-glycosylated proteins, rat CRP is a glycoprotein and contains a covalently linked dimer in the pentamer . The protein forms a homopentamer, with each subunit capable of binding two calcium ions .
CRP is secreted by the liver in response to factors released by fat cells (adipocytes). Its primary function is to bind to phosphocholine on the surface of dying cells and some bacteria, which helps to activate the complement system, promoting phagocytosis by macrophages .
Recombinant rat CRP is typically produced using bacterial expression systems. The gene encoding rat CRP is cloned into an expression vector, which is then introduced into a bacterial host such as Escherichia coli. The bacteria are cultured, and the recombinant protein is expressed and subsequently purified using techniques such as affinity chromatography .
Recombinant rat CRP is widely used in research to study inflammation and immune response. It is utilized in various assays, including ELISA (Enzyme-Linked Immunosorbent Assay), to measure CRP levels in biological samples such as serum, plasma, urine, and cell culture supernatants . These assays help in understanding the role of CRP in different physiological and pathological conditions.