Amyloid kidney stones of uremic patients consist of beta 2-microglobulin fragments.
Urinary stones with amyloid structure, obtained from uremic patients, were analyzed according to molecular weight, amino acid sequence, and antigenic content. A major protein of approximately 7 kD, designated AB protein, was isolated by size exclusion using HPLC in 60% formic acid. AB protein reacted in immunodiffusion only with an antiserum to beta 2-microglobulin, with beta 2m spurring over AB protein. N-terminal amino acid sequence analysis defined two fragments homologous to beta 2m. One fragment commenced with Ile at position 7 and the other with Ser at position 20, with a cleavage point subsequent to a lysyl residue in both. It is concluded that beta 2m is a precursor of urinary amyloid stones and intratubular concretions of patients with preterminal and terminal renal failure; limited proteolysis is involved in AB amyloid generation.
D000595:Amino Acid Sequence; D000682:Amyloid / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006801:Humans; D005779:Immunodiffusion; D007669:Kidney Calculi / Q000209:etiology / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments; D011498:Protein Precursors / Q000032:analysis; D014511:Uremia / Q000150:complications*; D001613:beta 2-Microglobulin / Q000032:analysis*
D000682:Amyloid; D010446:Peptide Fragments; D011498:Protein Precursors; D001613:beta 2-Microglobulin