1.C.92 The Pentraxin (Pentraxin) Family

The pentraxins are a family of highly conserved plasma proteins of metazoans known to function in immune defence. The canonical members, C-reactive protein and serum amyloid P component, have been identified in arthropods and humans. Mammalian pentraxins are known to bind lipid bilayers, and a pentraxin representative from the American horseshoe crab, Limulus polyphemus, binds and permeabilizes mammalian erythrocytes. Both activities are Ca2+-dependent. Utilizing model liposomes and planar lipid bilayers, all of the Limulus pentraxins permeabilize lipid bilayers (Harrington et al., 2008). Mechanistically, Limulus C-reactive protein forms transmembrane pores in asymmetric planar lipid bilayers that mimic the outer membrane of Gram-negative bacteria and exhibits a Ca2+-independent form of membrane binding that may be sufficient for pore formation.

The reaction catalzed by pentraxins is:

small molecules (in) small molecules (out)



Harrington, J.M., H.T. Chou, T. Gutsmann, C. Gelhaus, H. Stahlberg, M. Leippe, and P.B. Armstrong. (2008). Membrane pore formation by pentraxin proteins from Limulus, the American horseshoe crab. Biochem. J. 413: 305-313.

Lee, S.J., M. Wei, C. Zhang, S. Maxeiner, C. Pak, S. Calado Botelho, J. Trotter, F.H. Sterky, and T.C. S├╝dhof. (2017). Presynaptic Neuron.al Pentraxin Receptor Organizes Excitatory and Inhibitory Synapses. J. Neurosci. 37: 1062-1080.

Matthews, P.M., A. Pinggera, D. Kampjut, and I.H. Greger. (2021). Biology of AMPA receptor interacting proteins - From biogenesis to synaptic plasticity. Neuropharmacology 197: 108709.


TC#NameOrganismal TypeExample
1.C.92.1.1C-reactive protein 1.1 precursor, CRP1.1AnimalsCRP1.1 of Limulus polyphemus (P06205)
1.C.92.1.2Serum amyloid P component precursor, SAP (223aas)AnimalsSAP of Homo sapiens (P02743)

Neuronal pentraxin receptor-1 (NPR1) of 432 aas and 1 or 2 N-terminal TMSs.  May be involved in mediating uptake of synaptic material during synapse remodeling or in mediating the synaptic clustering of AMPA glutamate receptors at a subset of excitatory synapses. NPR is a potent inducer of both excitatory and inhibitory heterologous synapses; knockdown of NPR in cultured neurons decreases the density of both excitatory and inhibitory synapses (Lee et al. 2017). NPR1 is an auxiliary subunit of AMPA receptors (Matthews et al. 2021).

NPR1 of Homo sapiens