Hwang K M, Yang L C, Carrico C K, Schulz R A, Schenkman J B, Sartorelli A C
J Cell Biol. 1974 Jul;62(1):20-31. doi: 10.1083/jcb.62.1.20.
Inhibitors of protein synthesis capable of differential effects on nascent peptide synthesis on membrane-bound and free polyribosomes were employed to investigate the structure and function of cellular membranes of liver. The formation of membranous whorls in the cytoplasm and distension of nuclear membranes were induced by inhibitors of protein synthesis (i.e., cycloheximide and emetine) which predominantly interfere with nascent peptide synthesis on membrane-bound polyribosomes in situ. Other inhibitors of protein synthesis such as puromycin and fusidic acid, which inhibit nascent peptide synthesis on both free and membrane-bound polyribosomes, and chloramphenicol, which inhibits mitochondrial protein synthesis, did not induce these alterations. Cycloheximide, puromycin, and chloramphenicol produce some common cellular lesions as reflected by similar alterations in morphology, such as swelling of mitochondria, degranulation of rough endoplasmic reticulum, and aggregation of free ribosomes. The process of whorl formation in the cytoplasm, the incorporation of [(3)H]leucine and of [(3)H]choline into endoplasmic reticulum and the total NADPH-cytochrome c reductase activity of the endoplasmic reticulum were determined. During maximum formation of membranous whorls, [(3)H]leucine incorporation into cytoplasmic membranes was inhibited, while [(3)H]choline incorporation into these structures was increased; maximum inhibition of protein synthesis and stimulation of choline incorporation into endoplasmic reticulum, however, preceded whorl formation. Cycloheximide decreased the activity of NADPH-cytochrome c reductase of rough endoplasmic reticulum, but increased NADPH-cytochrome c reductase activity of smooth endoplasmic reticulum. In addition, cycloheximide decreased the content of hemoprotein in both the microsomal and mitochondrial fractions of rat liver, and the activities of mixed function oxidase and of oxidative phosphorylation were impaired to different degrees. Succinate-stimulated microsomal oxidation was also inhibited. The possible mechanisms involved in the formation of membranous whorls, as well as their functions, are discussed.
利用能够对膜结合多核糖体和游离多核糖体上新生肽合成产生不同影响的蛋白质合成抑制剂，来研究肝细胞膜的结构和功能。蛋白质合成抑制剂（即环己酰亚胺和依米丁）可诱导细胞质中膜性涡旋的形成和核膜扩张，这些抑制剂主要干扰原位膜结合多核糖体上的新生肽合成。其他蛋白质合成抑制剂，如嘌呤霉素和夫西地酸，它们抑制游离和膜结合多核糖体上的新生肽合成，以及抑制线粒体蛋白质合成的氯霉素，均未诱导这些改变。环己酰亚胺、嘌呤霉素和氯霉素会产生一些常见的细胞损伤，这可通过形态学上的相似改变反映出来，如线粒体肿胀、糙面内质网脱颗粒以及游离核糖体聚集。测定了细胞质中涡旋形成过程、[³H]亮氨酸和[³H]胆碱掺入内质网的情况以及内质网的总NADPH - 细胞色素c还原酶活性。在膜性涡旋形成的高峰期，[³H]亮氨酸掺入细胞质膜受到抑制，而[³H]胆碱掺入这些结构增加；然而，蛋白质合成的最大抑制和胆碱掺入内质网的刺激在涡旋形成之前。环己酰亚胺降低了糙面内质网的NADPH - 细胞色素c还原酶活性，但增加了滑面内质网的NADPH - 细胞色素c还原酶活性。此外，环己酰亚胺降低了大鼠肝脏微粒体和线粒体部分的血红蛋白含量，混合功能氧化酶和氧化磷酸化的活性也受到不同程度的损害。琥珀酸刺激的微粒体氧化也受到抑制。文中讨论了膜性涡旋形成可能涉及的机制及其功能。
