. 2023 Oct 9;14:1274634. doi: 10.3389/fimmu.2023.1274634

Table 1.

Major interactions of PTX3 and their functional outcomes.

	Ligand	Binding interface	Function	Refs.
Microorganisms	SARS-CoV-2	Nucleocapsid protein recognition by the PTX3 N-term	Prognostic indicator of short-term mortality in COVID-19	(41–43)
	Influenza virus	Viral hemagglutinin binding to sialic acid residues of the PTX3 C-term	Inhibition of hemagglutination, neutralization of virus infectivity, inhibition of viral neuraminidase	(44)
	Cytomegalovirus	Unknown	Inhibition of viral entry and infectivity in vitro, protection from murine CMV infection/reactivation and A. fumigatus superinfection in vivo	(45)
	A. fumigatus	Unknown cell wall ligand binding to the PTX3 N-term	Opsonization, promotion of phagocytosis and killing by neutrophils via complement and Fcγ receptors	(35, 46)
	K. pneumoniae	Ca²⁺-dependent recognition of KpOmpA (binding site on PTX3 unknown)	Amplification of the inflammatory response in vivo	(47)
	N. meningitidis	Ca²⁺-independent binding of meningococcal antigens GNA0667, GNA1030 and GNA2091 to the PTX3 N-term	Amplification of the antibody response and protection from infection in vivo	(48)
	E. coli	Unknown	Protection from urinary tract infection	(49)
Receptors	P-selectin	P-selectin binding to sialic acid residues of the PTX3 C-term	Inhibition of leukocyte extravasation	(50)
	FcγRIIa and III	Unknown	Promotion of phagocytosis	(46)
	CD44	209-217aa and 352-360aa regions of the PTX3 C-term	Osteogenesis and cancer growth/metastasis and	(13, 14)
Hemostasis	Fibrinogen/Fibrin	pH-dependent binding to the PTX3 N-term	Enhancement of plasmin-mediated fibrinolysis	(40)
Hemostasis	Plasminogen	pH-dependent binding of the KR3-KR5 domains to the PTX3 N-term	Enhancement of plasmin-mediated fibrinolysis	(40)
Angiogenesis	FGF2	97-110aa sequence of the PTX3 N-term	Inhibition of angiogenesis, restenosis and cancer progression	(51–55)
Angiogenesis	FGF8	Unknown		(51–55)
Complement	C1q	Sialic acid-dependent binding to the globular head of C1q (mainly through B chain Arg residues)	Control of the CP	(56, 57)
	C3b	Unknown	Inhibition of the AP	(10)
	fH proteins	Ca²⁺- and glycosylation-dependent recognition of CCP7 of fH and FHL-1 (by the PTX3 C-term) and CCP19-20 of fH and FHR1 (by the PTX3 N-term)	Inhibition of the AP	(10, 58–61)
	C4BP	Ca²⁺-dependent recognition of SCRs 1-3 of the C4BP α-chain (binding site on PTX3 unknown)	Inhibition of the CP/LP	(62)
	MBL	Unknown	Cross-activation of the LP	(63)
	Ficolins	Glycosylation-dependent interaction	Cross-activation of the LP	(64)
ECM	IαI	Mg²⁺-dependent binding of the PTX3 N-term to HCs 1 and 2 of IαI	Assembly and stability of the HA ECM	(33, 65–67)
	TSG6	Link module recognition by the PTX3 N-term	Assembly and stability of the HA ECM and regulation of angiogenesis	(55, 67)
	TSP1	C-terminal globular domain (E123CaG-1) binding to the PTX3 N-term	Control of synaptogenesis	(68)
Others	Histones	N-term domain of histones (binding site on PTX3 unknown)	Protective functions against extracellular histone-mediated cytotoxicity	(32)