细胞色素c的生物合成。[14C]赖氨酸在大鼠肝脏亚细胞组分中体内掺入细胞色素c和总蛋白的序列。

The biosynthesis of cytochrome c. Sequence of incorporation in vivo of [14C]lysine into cytochrome c and total proteins of rat-liver subcellular fractions.

作者信息

González-Cadavid N F, Campbell P N

出版信息

Biochem J. 1967 Nov;105(2):443-50. doi: 10.1042/bj1050443.

DOI:10.1042/bj1050443

PMID:5583987

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1198329/

Abstract

In order to determine the initial intracellular site of synthesis of cytochrome c in the liver cell, groups of rats were injected with [(14)C]lysine and killed 7.5, 15, 30 and 60min. later. The livers were homogenized in 0.3m-sucrose and subcellular fractions obtained. The mitochondrial fraction was further subfractionated. Pure cytochrome c was isolated from extracts of each fraction, obtained first with water at pH4.0 and then with 0.15m-sodium chloride. 2. A comparison of the kinetics of incorporation of [(14)C]lysine into total protein for each particulate fraction showed the usual two different kinds of kinetics. Incorporation into all the mitochondrial subfractions and the nuclear fraction rose gradually to a plateau value at about 20min., in contrast with that into the two microsomal fractions which rose rapidly to a peak value about seven times that for the mitochondrial fractions. The kinetics for the incorporation into mitochondrial cytochrome c showed a plateau value at 30min. about three times that for the total mitochondrial protein. There was no difference in the specific radioactivity of the mitochondrial cytochrome c extracted with water or 0.15m-sodium chloride or between the different mitochondrial subfractions. In contrast, the cytochrome c isolated from water extracts of the microsomal fractions had a lower specific radioactivity than that obtained from the 0.15m-sodium chloride extract. The specific radioactivity of the latter showed a rapid rise to a peak value about four times that for the mitochondrial cytochrome c, and the shape of the curve was similar to that for the total protein of the microsomal fraction. The results suggest that cytochrome c is synthesized in toto by the morphological components of the microsomal fraction. It seems first to be bound tightly to a microsomal particle, passing then to a looser microsomal binding and being finally transferred to the mitochondria. The newly synthesized cytochrome c in the mitochondrion could not be differentiated from the old by its degree of extractability at pH 4.0.

摘要

为了确定肝细胞中细胞色素c合成的初始细胞内位点，给几组大鼠注射[¹⁴C]赖氨酸，并在7.5、15、30和60分钟后处死。将肝脏在0.3m蔗糖中匀浆，得到亚细胞组分。线粒体组分进一步细分。从每个组分的提取物中分离出纯细胞色素c，先用pH4.0的水提取，然后用0.15m氯化钠提取。2. 对每个颗粒组分中[¹⁴C]赖氨酸掺入总蛋白的动力学进行比较，显示出通常的两种不同动力学。掺入所有线粒体亚组分和核组分的量在约20分钟时逐渐上升至平稳值，这与掺入两个微粒体组分的情况形成对比，后者迅速上升至约为线粒体组分峰值七倍的峰值。掺入线粒体细胞色素c的动力学在30分钟时显示出平稳值，约为线粒体总蛋白的三倍。用水或0.15m氯化钠提取的线粒体细胞色素c的比放射性没有差异，不同线粒体亚组分之间也没有差异。相比之下，从微粒体组分的水提取物中分离出的细胞色素c的比放射性低于从0.15m氯化钠提取物中获得的比放射性。后者的比放射性迅速上升至约为线粒体细胞色素c峰值四倍的峰值，曲线形状与微粒体组分总蛋白的曲线形状相似。结果表明，细胞色素c完全由微粒体组分的形态成分合成。它似乎首先紧密结合到微粒体颗粒上，然后转移到较松散的微粒体结合物上，最终转移到线粒体中。线粒体中新合成的细胞色素c在pH 4.0时的可提取程度与旧的细胞色素c没有区别。