Terada K, Kawarada Y, Miura N, Yasui O, Koyama K, Sugiyama T
Department of Biochemistry, Akita University School of Medicine, Japan.
Biochim Biophys Acta. 1995 Jan 25;1270(1):58-62. doi: 10.1016/0925-4439(94)00072-x.
Ceruloplasmin, a blue copper oxidase found in plasma, is synthesized in hepatocytes as a single polypeptide chain consisting of a 19 amino acid leader peptide plus 1046 amino acids of mature protein (132 kDa). Holoceruloplasmin is secreted into the plasma with 6-7 atoms of copper bound per molecule. In this study we identified apo- and holoceruloplasmin and examined the mechanism of copper incorporation during ceruloplasmin biosynthesis using the Long-Evans Cinnamon (LEC) rat which does not incorporate copper into newly synthesized ceruloplasmin. We followed the conversion from ceruloplasmin precursor (with little or no carbohydrate) to the larger product (after carbohydrate addition), which occurred in the secretory compartments of hepatocytes, by native gel electrophoresis. We found that copper accumulates in the hepatocellular Golgi apparatus of LEC rats due to a disorder in the process of copper incorporation. The data indicate that copper is incorporated into ceruloplasmin late in the course of its transport through the secretory compartments.
铜蓝蛋白是一种存在于血浆中的蓝色铜氧化酶，在肝细胞中作为由19个氨基酸的前导肽加1046个氨基酸的成熟蛋白（132 kDa）组成的单条多肽链合成。全铜蓝蛋白以每个分子结合6 - 7个铜原子的形式分泌到血浆中。在本研究中，我们鉴定了脱辅基铜蓝蛋白和全铜蓝蛋白，并使用不能将铜掺入新合成的铜蓝蛋白中的长 Evans 肉桂色（LEC）大鼠，研究了铜蓝蛋白生物合成过程中铜掺入的机制。我们通过非变性凝胶电泳追踪了铜蓝蛋白前体（几乎没有或没有碳水化合物）向更大产物（添加碳水化合物后）的转化，这种转化发生在肝细胞的分泌区室中。我们发现，由于铜掺入过程中的紊乱，铜在LEC大鼠的肝细胞高尔基体中积累。数据表明，铜在其通过分泌区室的运输过程后期掺入铜蓝蛋白。
