All amyloid deposits contain SAP (APCS), a glycoprotein that belongs to the pentraxin family (PTXs) and binds amyloid independently of the protein of origin. It has a specific binding motif for the common conformation of amyloid fibrils. This property makes radiolabeled SAP a diagnostic tool for the imaging of amyloid deposits. SAP (APCS) is highly protected against proteolysis and thus makes amyloid fibrils resistant to degradation.
See also
PTXs (pentraxins)