Abstract
Synthesis and secretion of the protein with molecular weight 196 K on SDS-polyacrylamide gel electrophoresis was induced in immature Japanese eel hepatocytes by pharmacologically high concentration of estradiol-17β (E2), 10-4M, during 4 days culture, but it was not induced by 10-5M and 10-6M E2 during the same or more days culture. The protein with the same molecular weight was observed in the plasma of the eel into which E2 was injected intraperitoneally.
Vitellogenin, a very-high-density lipoprotein with density in the range of 1.27 to 1.30g/ml, was isolated from the plasma of female silver eel and also from that of E2 treated immature eels by density gradient ultracentrifugation. This lipoprotein was further purified by a DEAE-Toyopearl column and characterized to consist of a major apolipoprotein with 196 K. These results in dicate that the 196 K protein that appeared in the culture medium of hepatocytes is the apolipoprotein of vitellogenin.
Hepatocytes prepared from the preliminarily E2-injected eel secreted the vitellogenin after 3 days culture with 10-6M E2, but did not secrete the vitellogenin after the same or more days culture without E2.
