Three tRNA binding sites have been found in organisms of all domains (former kingdoms) with only one exception: Four binding sites have been reported for cytoplasmic 80S ribosomes from rabbit liver. Therefore, the issue was reconsidered, and the data revealed that rabbit liver ribosomes contain three tRNA binding sites, underlining the universal character of this ribosomal feature. Furthermore, a first analysis of the role of the ribosome intrinsic ATPase was performed. This ATPase is found in ribosomes of higher eukarya but not in lower eukarya such as yeast or ribosomes of the domains archea and bacteria. The results suggest that the intrinsic ATPase fulfills the same function as the essential third elongation factor EF-3, an ATPase in higher fungi (yeast etc.), that facilitates the release of the deacylated tRNA from the E site.
To determine the paracrine effect of cultured fibroblasts on HeLa cell motility and mTOR/ S6K1 phosphorylation status in vitro. Background. High cancer cell motility is a feature of the malignant tumor. The mTOR/S6K1 signaling network is one of the key links in regulation of cell migration. The cancer cell motility is also dependent on the tumor microenvironment but the effect of stroma on cancer cell migration is insufficiently studied. Methods. Cell culture, Western blot analysis, scratch test, statistical analysis. Results. Application of the media conditioned by a highly confluent monolayer culture of primer human dermal fibroblasts or NIH 3T3 fibroblasts leads to a significant increase of the mTOR and S6K1 phosphorylation in HeLa cells. These conditioned media also have an inhibitory effect on the motility of tumor cells similar to that of mTOR/S6K1 signaling inhibitor rapamycin. Moreover, the combination of rapamycin and fibroblast-conditioned medium does not additionally change the cancer cell motility in comparison to rapamycin or fibroblast conditioned medium alone. Conclusion. The tumor microenvironment can significantly modulate the behavior of cancer cells and the efficiency of anticancer drugs. This should be taken into consideration when developing anticancer drugs.
Институт молекулярной биологии и генетики НАН Украины 252143, Киев, ул. Академика Заболотного, 150 Разработана реконструированная бесклеточная белоксинтезирующая система из печени кролика, содержащая высокоочищенные гомологичные компон енты аппарата трансляции. Использование спермина и спермидина позволило оптимизировать активность системы при физиологических концентрациях Mg**.
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