SIEKEVITZ P, PALADE G E
J Biophys Biochem Cytol. 1959 Jan 25;5(1):1-10. doi: 10.1083/jcb.5.1.1.
Five ribonucleoprotein (RNP) fractions were isolated from the postmitochondrial supernatant of the pancreas of the guinea pig. Two were obtained from the microsomes which, by deoxycholate (DOC) treatment, were subdivided into a DOC-soluble and a DOC-insoluble fraction. The latter was taken to represent attached RNP particles. Two other fractions obtained from the microsomal supernatant supposedly represent free RNP particles existing as such in the cytoplasm, while a third fraction resisted sedimentation for 20 hours at 105,000 g and is considered to be a soluble nucleoprotein. These fractions exhibited different RNA/protein ratios and also different RNA turnover patterns, as determined after in vivo labelling with adenine-8-C(14). However, little discernible differences could be detected in the nucleotide composition of the RNA moieties of these RNP fractions. Amino acid-"activating" enzymes were found to occur in the fraction containing the soluble nucleoproteins. The discussion focuses on the relationships between these fractions and protein synthesis in the pancreas, using data given in this and a previous paper, and data contained in the literature.
从豚鼠胰腺的线粒体后上清液中分离出了五个核糖核蛋白（RNP）组分。其中两个组分来自微粒体，通过脱氧胆酸盐（DOC）处理，微粒体被细分为DOC可溶性组分和DOC不溶性组分。后者被认为代表附着的RNP颗粒。从微粒体上清液中获得的另外两个组分据推测代表在细胞质中以这种形式存在的游离RNP颗粒，而第三个组分在105,000 g下离心20小时仍未沉降，被认为是一种可溶性核蛋白。在用腺嘌呤-8-C（14）进行体内标记后测定发现，这些组分表现出不同的RNA/蛋白质比率以及不同的RNA周转模式。然而，在这些RNP组分的RNA部分的核苷酸组成中几乎检测不到明显差异。在含有可溶性核蛋白的组分中发现了氨基酸“活化”酶。利用本文及之前一篇论文中的数据以及文献中包含的数据，讨论集中在这些组分与胰腺中蛋白质合成之间的关系上。
