Pentraxin-related protein PTX3 is a long pentraxin that provides defence against infectious agents and plays several functions in tissue repair and regulation of cancer-related inflammation [].Pentraxins are a family of evolutionarily conserved molecules with regulatory role in inflammation. They share the "pentraxin signature"(His-x-Cys-x-Ser/Thr-Trp-x-Ser, where x is any amino acid) and can be divided into a short and a long arm based on their structural organization. Short pentraxins, feature a peculiar quaternary structure with five or ten identical protomer subunits arranged into symmetric pentamers, such as CRP and SAP, are secreted proteins produced by hepatocytes in response to IL-6. Long pentraxins, on the other end, display an unrelated amino-terminal region coupled to a C-terminal pentraxin domain. PTX3 is the prototype of the long pentraxin subfamily produced by myeloid and stromal cells, but not by hepatocytes, in response to primary pro-inflammatory cytokines or microbial moieties [].
Pentaxins (or pentraxins) [, ]are a family of proteins which show, underelectron microscopy, a discoid arrangement of five noncovalently boundsubunits. Proteins known to belong to this family are:C-reactive protein (CRP), a protein which, in mammals,is expressed duringacute phase response to tissue injury or inflammation. CRP displays severalfunctions associated with host defense: it promotes agglutination,bacterial capsular swelling, phagocytosis and complement fixation throughits calcium-dependent binding to phosphorylcholine. CRPs have also beensequenced in an invertebrate, the Atlantic horseshoe crab, where they are anormal constituent of the hemolymph.Serum Amyloid P-component (SAP), a precursor of amyloid component P whichis found in basement membrane and is associated with amyloid deposits.Hamster female protein (FP), a plasma protein whose concentration isaltered by sex steroids and stimuli that elicit an acute phase response.A number of proteins, whose function is not yet clear, contain a C-terminalpentaxin-like domain. These proteins are:Human PTX3 (or TSG-14). PTX3 is a cytokine-induced protein.Guinea pig apexin [], a sperm acrosomal protein. Apexin seems to be theortholog of human neuronal pentraxin II (gene NPTX2) [].Rat neuronal pentaxin I [].The sequences of the different members of this family are quite conserved. This entry represents a six residue pattern which includes a cysteineknown to be involved in a disulfide bridge in CRPs and SAP.
