The present studies show that the previously reported ability of fetuin to inhibit the
precipitation of hydroxyapatite from supersaturated solutions of calcium and phosphate in
vitro is accompanied by the formation of the fetuin-mineral complex, a high molecular mass
complex of calcium phosphate mineral and the proteins fetuin and matrix Gla protein that
was initially discovered in the serum of rats treated with etidronate and that appears to play a
critical role in inhibiting calcification in vivo. Rat serum potently inhibited the precipitation of …