Analogues in other mammals and in fish of human plasma proteins, C-reactive protein and amyloid P component

Crystal structures for short-chain pentraxin from zebrafish demonstrate a cyclic trimer with new recognition and effector faces

“…Although the innate immune system can be found in representative species at nearly every level of the evolutionary tree, PTX genes emerged in arthropods and are phylogenetically conserved throughout all vertebrate organisms, such as fish, amphibians, reptiles, birds and mammals (Huong Giang et al, 2010;Iwaki et al, 1999;Lin and Liu, 1993;Pepys et al, 1978;Rubio et al, 1993). Unexpectedly, seven different PTX loci are located consecutively in an identical region of chromosome 24 in the zebrafish genome (Falco et al, 2012).…”

“…The pentraxin superfamily is divided into two subclasses: classical short-chain pentraxins, such as C-reactive protein (CRP) and serum amyloid P-component (SAP) (Pepys et al, 1978), and longchain pentraxins (Goodman et al, 1996). Short-chain pentraxins are soluble pattern recognition receptors produced in the liver in response to inflammatory signals and subsequently act as multifunctional antibodies in the innate immune system (Ganapathi et al, 1991;Lu et al, 2012).…”

Hamster female protein, a sex-limited pentraxin, is a constituent of Syrian hamster amyloid.

“…AP exists as a normal human serum constituent (called serum AP or SAP) and has been shown to be structurally similar (50-70% homology) to human C-reactive protein (CRP) (6,7). Homologues of human SAP and CRP have been found in a variety of animals (8,9) and belong to a family of proteins called pentraxins (6). Pentraxins from horseshoe crab (10), telost fish (9,11), and humans are remarkably similar in structure and this conservative evolution implies an important but as yet unproven function for these proteins.…”

Significance of serum c‐reactive protein elevation in patients with systemic lupus erythematosus

“…Recent studies have substantially increased our understanding of the structure, function, and mechanism of formation of this protein. CRP shows marked amino acid homology and structural similarity to protein SAP (serum amyloid component), a serum protein apparently identical to the P component of amyloid; both of these proteins manifest calcium-dependent ligand binding (6)(7)(8). The ability of CRP to activate the complement system upon reaction with phosphoryl choline moieties and a number of other tissue-derived substrates (9,10), as well as its ability to inhibit platelet function (1 l), suggests that it plays a role in modulating the inflammatory response.…”