Alpha2-macroglobulin is a potential facilitator of prion protein transformation.

Cellular prion protein changes conformation during transformation to an infectious scrapie isoform. One measure of transformation is the development of partial resistance to protease treatment. A fraction of human and bovine plasma was identified containing activity that facilitates transformation of cellular prion protein to a protease resistant isoform in the presence of RNA in the absence of seeded scrapie prion protein. Purification of proteins from this fraction led to the identification of alpha2-macroglobulin as an active component suggesting that it may facilitate conformational changes in prion protein in spontaneous forms of prion disease.