Summary:
The highly conserved family of pentraxins (short pentraxins, CRP and SAP) consists of approximately 25 000
(mW)proteins. Recently, several distinct larger proteins expressed in the brain and other tissues have been
identified.
PTX3 was the first cloned member of the long pentraxin family. From 1993, other long pentraxins were
identified, including NPR, XL-PXN1 from Xenopus laevis, rat and human neuronal pentraxin NP1, neuronal
pentraxin NP2, which possibly represents the human homologue of guinea pig pentraxin apexin, and rat
pentraxin Narp. In all these molecules a C-terminal pentraxin domain is clearly related to serum pentraxins, the
N-terminal domain shows no strong homology to other known proteins.
Long pentraxins exhibit structural and functional similarities as well as differences when compared with the
classical pentraxins. Long pentraxins do not have the restricted liver inducibility typical of CRP and SAP (upon
interleukin-6 stimulation) and show a more premiscuous pattern of expression in vitro and in vivo. PTX3 is
inducible by TNF or IL-1 and is produced during the acute phase response. Other newly identified long pentraxins
are constitutively expressed proteins.
The function of long pentraxins is unknown. They may play important roles in the uptake of extracellular
material in various tissues as well as in apoptosis of neuronal cells.
Key words:
apoptosis, tumour necrosis factor, interleukin-1, pentraxins.
|