SIEKEVITZ P, PALADE G E
J Biophys Biochem Cytol. 1958 May 25;4(3):309-18. doi: 10.1083/jcb.4.3.309.
Microsomes were isolated from the pancreas of starved and fed guinea pigs. In the first case, the gland was removed from animals starved for 48 hours; in the second, the pancreas was excised 1 hour after the beginning of a meal that ended a fast of 48 hours. These are referred to below as fed animals. In both cases the tissue was homogenized in 0.88 M sucrose and the microsomes obtained by centrifuging the mitochondrial supernatant at 105,000 g for 60 minutes. In starved animals the content of the endoplasmic reticulum of the exocrine cells and the content of the microsomes were found to be of low or moderate density. In fed guinea pigs the cavities of the reticulum frequently contained dense intracisternal granules and the microsomes were distinguished by a content of high density sometimes in the form of recognizable intracisternal granules. In starved animals, the microsomes were found to account for 5 to 20 per cent of the trypsin-activatable proteolytic activity and ribonuclease activity of the whole cell, whereas in fed animals they contained uniformly almost 30 per cent of these activities. In fed animals the dense, cohesive content of the microsomes (intracisternal granules) could be isolated by breaking up the microsomes with dilute (0.1 per cent) deoxycholate solutions and separating microsomal subfractions by differential centrifugation. The specific enzymatic activities of a heavy microsomal subfraction rich in intracisternal granules were almost equal to those of isolated purified zymogen granules. The ribonucleoprotein particles attached to the microsomal membranes could be isolated by the same technique and found also to exhibit some of the same enzymatic activities. Corresponding subfractions isolated from the microsomes of starved animals were considerably less active. The relevance of these findings for the synthesis and intracellular transport of protein in the exocrine cell of the pancreas is discussed.
从饥饿和进食的豚鼠胰腺中分离出微粒体。在第一种情况下，从饥饿48小时的动物身上取出腺体；在第二种情况下，在结束48小时禁食的进食开始1小时后切除胰腺。以下将这些动物称为进食动物。在这两种情况下，组织均在0.88M蔗糖中匀浆，并通过在105,000g下离心线粒体上清液60分钟获得微粒体。在饥饿动物中，外分泌细胞内质网的含量和微粒体的含量为低密度或中等密度。在进食的豚鼠中，内质网腔中经常含有密集的池内颗粒，微粒体的特征是有时含有高密度的物质，呈可识别的池内颗粒形式。在饥饿动物中，发现微粒体占全细胞胰蛋白酶可激活的蛋白水解活性和核糖核酸酶活性的5%至20%，而在进食动物中，它们几乎均匀地含有这些活性的30%。在进食动物中，通过用稀释的（0.1%）脱氧胆酸盐溶液破碎微粒体并通过差速离心分离微粒体亚组分，可以分离出微粒体的密集、凝聚性内容物（池内颗粒）。富含池内颗粒的重微粒体亚组分的比酶活性几乎与分离的纯化酶原颗粒的比酶活性相等。附着在微粒体膜上的核糖核蛋白颗粒可以通过相同的技术分离出来，并且也发现具有一些相同的酶活性。从饥饿动物的微粒体中分离出的相应亚组分活性明显较低。讨论了这些发现与胰腺外分泌细胞中蛋白质合成和细胞内运输的相关性。
