Pentraxin 4, Long (PTX4)

PTX4 belongs to the pentraxin (PTX) superfamily of multifunctional conserved proteins. Pentraxins are characterized by a cyclic multimeric structure and a conserved C-terminal pentraxin domain of approximately 200 amino acids. All pentraxins have a conserved 8-amino acid sequence, HxCxS/TWxS, in which x is any amino acid, within their pentraxin domain.

Pentraxins are divided into short proteins, such as C-reactive protein (CRP) and serum amyloid P protein (APCS), and long proteins, such as PTX3 and PTX4. Some PTXs are part of the humoral arm of innate immunity and behave as functional ancestors of antibodies by mediating agglutination, complement activation, and opsonization.