Serum ferritin is characterized by a high representation of the 17-kD truncated subunit of the L-chain. (A) Serum or tissue-lysates from iron-dextran overloaded mice were subjected to IP, using an anti–liver ferritin antibody (Serum, 20 μg ferritin/IP; liver lysate, 200 μg protein/IP; and all other tissue lysates, 1 mg protein/IP). IPs were separated on SDS-PAGE and stained with Coomassie (top panel; 1 representative experiment is shown of 4). Western blot with anti–liver ferritin antibody from tissue-lysates (40 μg protein/IP) and immunoprecipitated serum from iron-dextran overloaded mice (bottom panel; 1 representative experiment is shown of 3). (B) Western blot as in panel A from tissue lysates (40 μg protein/lane) and serum (200 ng of ferritin/IP) from untreated mice (1 representative experiment is shown of 3).