Can interact with DNA and histones and may scavenge nuclear material released from damaged circulating cells. May also function as a calcium-dependent lectin. Binds 2 calcium ions per subunit. Homopentamer. Pentraxin (or pentaxin) have a discoid arrangement of 5 non-covalently bound subunits. Found in serum and urine. N-glycosylated with a complex biantennary oligosaccharide chain with a sialic acid at the end (disialo-SAP). Monosialo-SAP as well as asioalo-SAP are also detected (PubMed:15174148). SAP is a precursor of amyloid component P which is found in basement membrane and associated with amyloid deposits. Belongs to the pentraxin family. Serum amyloid P component entry