Binding of ceruloplasmin to bovine erythrocytes was investigated. The
interaction was specific as demonstrated by more than 85% inhibition b
y excess ceruloplasmin protein. Binding was also inhibited by copper-n
itrilotriacetate. The K-D for both intact erythrocytes and solubilized
ghost membranes was of the order of 10(-7) M. Using an affinity colum
n a specific ceruloplasmin-binding protein was isolated from ghost mem
branes. The protein has an apparent molecular mass of 100,000 with sub
units of 45 and 50 KDa.