Pentraxins

Pentraxins

Structure of C-reactive protein (CRP), a member of the pentraxin family.

Pentraxins are a family of proteins characterized by their cyclic multimeric structure. They play a crucial role in the innate immune system by recognizing pathogens and damaged cells, thereby facilitating their clearance. The most well-known members of this family are C-reactive protein (CRP) and serum amyloid P component (SAP).

Structure

Pentraxins are defined by their pentameric structure, which is a ring-like arrangement of five identical subunits. This structure is stabilized by non-covalent interactions. The pentraxin domain is highly conserved and is responsible for calcium-dependent ligand binding. The structure of CRP, for example, reveals a discoid shape with a central pore, which is typical of pentraxins.

Function

Pentraxins are involved in the acute phase response, a rapid inflammatory response to tissue injury or infection. They function as pattern recognition molecules, binding to specific molecular patterns on the surface of pathogens or apoptotic cells. This binding activates the complement system and promotes phagocytosis by macrophages and neutrophils.

C-reactive protein (CRP)

CRP is a major acute-phase protein in humans. It is synthesized by the liver in response to cytokines such as interleukin-6 (IL-6). CRP levels in the blood increase rapidly during inflammation, making it a useful clinical marker for inflammatory diseases and infection.

Serum amyloid P component (SAP)

SAP is another pentraxin that is involved in the clearance of cellular debris and the inhibition of amyloid fibril formation. It is found in all vertebrates and is highly conserved across species.

Clinical Significance

The measurement of CRP levels is commonly used in clinical practice to assess the presence and intensity of inflammation. Elevated CRP levels are associated with a variety of conditions, including bacterial infections, autoimmune diseases, and cardiovascular disease.

Related pages

• Innate immune system
• Acute phase response
• Complement system
• Phagocytosis