What is the role of amyloid protein structures in the pathogenesis of amyloidosis?

Updated: May 09, 2019
  • Author: Robert O Holmes, Jr, DO; Chief Editor: Herbert S Diamond, MD  more...
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Answer

Answer

In all forms of amyloidosis, the cell secretes the precursor protein in a soluble form that becomes insoluble at some tissue site, compromising organ function. All the amyloid precursor proteins are relatively small (ie, molecular weights 4000-25,000) and do not share any amino acid sequence homology. The secondary protein structures of most soluble precursor proteins (except for SAA and chromosomal prion protein [Prpc]) have substantial beta-pleated sheet structure, while extensive beta-sheet structure occurs in all of the deposited fibrils.

In some cases, hereditary abnormalities (primarily point mutations or polymorphisms) in the precursor proteins are present (eg, lysozyme, fibrinogen, cystatin C, gelsolin). In other cases, fibrils form from normal-sequence molecules (eg, AL, β2 M). In other cases, normal-sequence proteins can form amyloid, but mutations underlying inflammatory milieu accelerate the process (eg, TTR, beta protein precursor or CAPS).


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