Majamaa K, Oikarinen J
Biochem J. 1982 Jun 15;204(3):737-42. doi: 10.1042/bj2040737.
The labelling of the subunits of prolyl 4-hydroxylase tetramers was studied in freshly isolated chick-embryo tendon cells and in chick-embryo tissues. In the former both the alpha- and beta-subunits of the tetramer were labelled during a 4 h labelling and 2 h chase period, although the radioactivity in the beta-subunit was much lower than in the alpha-subunit. The corresponding subunits of the enzyme from 12-day chick-embryo cartilaginous bone and heart were labelled in 7 h, again the beta-subunit much less than the alpha-subunit, the ratio of radioactivity in the beta-subunit to that in the alpha-subunit (beta/alpha-radioactivity) being 0.20 and 0.32 respectively. The beta/alpha-radioactivity then increased almost linearily with time between 7 and 24 h, by 9.5-fold in the cartilaginous bone and 3-fold in the heart, and beta/alpha-radioactivity values above 1.0 were reached. The free beta-subunit-size protein (the beta'-protein), which is also present in cells, had been labelled quite heavily by 7 h. The beta/alpha-radioactivity at 7h, determined in four tissues with different ratios of prolyl hydroxylase tetramers to total immunoreactive protein (tetramer percentage), was low in tissues with a high tetramer percentage. It is thus proposed that only a minor fraction of the beta'-protein must be processed to the tetrameric beta-subunit and utilized in the synthesis of the prolyl 4-hydroxylase tetramers.
在新鲜分离的鸡胚肌腱细胞和鸡胚组织中研究了脯氨酰4-羟化酶四聚体亚基的标记情况。在前一种情况下，在4小时标记和2小时追踪期内，四聚体的α-和β-亚基均被标记，尽管β-亚基中的放射性远低于α-亚基。来自12日龄鸡胚软骨骨和心脏的该酶的相应亚基在7小时内被标记，同样β-亚基比α-亚基少得多，β-亚基与α-亚基中的放射性之比（β/α-放射性）分别为0.20和0.32。然后，β/α-放射性在7至24小时之间几乎呈线性增加，在软骨骨中增加9.5倍，在心脏中增加3倍，并且达到了高于1.0的β/α-放射性值。细胞中也存在的游离β-亚基大小的蛋白质（β'-蛋白质）在7小时时已被大量标记。在具有不同脯氨酰羟化酶四聚体与总免疫反应性蛋白质比例（四聚体百分比）的四种组织中测定的7小时时的β/α-放射性，在四聚体百分比高的组织中较低。因此，有人提出只有一小部分β'-蛋白质必须被加工成四聚体β-亚基并用于脯氨酰4-羟化酶四聚体的合成。
