Human high-density lipoprotein associated amyloid A protein. Structural characteristics, relation to apo A-I and A-II concentrations, and plasma clearance kinetics in the rat.

Five amyloid related low-molecular-weight apoproteins were isolated and characterized from the plasma high-density lipoprotein fraction of a patient with glomerulonephritis caused by basement membrane antibodies. Amino acid and carbohydrate analyses of apoSAA subfractions showed that they were non-glycosylated polypeptides rich in aspartic acid, glycine, glutamic acid, glutamine, and arginine. The apo SAA subtype pattern was similar to that described in some other pathological conditions. Following injections of the isolated SAA-rich high density lipoprotein fraction into rat circulation, similar disappearance curves were obtained for apoSAA and apo A-I.