Amyloid

Abstract

A family of fibrillar proteins depositing in different tissues in primary and secondary amyloidosis. Their molecules have a typical folded leaf structure (anti-parallel β-structure). Chemically they are composed of the two different types AL (amyloid light) and AA (amyloid associated). The amyloid AL fibres consist of light-chain immunoglobulins or their fragments, whereas amyloid AA consists of non-immunoglobulin fibroproteins. The precursor of amyloid A is a serum amyloid P (SAP) which belongs to an important group of acute phase proteins and is an integral part of high-density lipoproteins (HDL). Besides these two forms AL and AA, amyloid deposits comprise to a lesser extent the amyloid P (AP) component, whose precursor is serum amyloid P.