title: Uptake of transfer ribonucleic acid by normal and leukemic cells.
abstract: Uptake of tRNA (Escherichia coli) was demonstrated in the murine leukemia, L1210 and in a human lymphoblast (NC-37) cell lines. In both cell lines, uptake of tRNA was rapid, reaching a maximum within 45 sec, and was linear with concentration up to about 50 mug/ml. This uptake of exogenous tRNA apparently was not due to altered membrane permeability or impaired cell viability, nor to ribonuclease degradation of the macromolecule. Furthermore, about 20% of the tRNA taken up by the cells remains functional and apparently intact. This was demonstrated by: (a) acylation with E. coli aminoacyl-tRNA synthetases; (b) methylation with leukemic cell tRNA-methylases, and (c) demonstrating (14)C-labeled 4S RNA in the cytoplasmic fraction of the leukemic cells after the addition of E. coli [(14)C]tRNA. The results demonstrate that tRNA can enter mammalian cells and suggest that an energy independent, carrier-mediated, mechanism may be operative.
mesh_terms: D000818:Animals; D001345:Autoradiography; D001692:Biological Transport; D002247:Carbon Isotopes; D002460:Cell Line / Q000378:metabolism; D002850:Chromatography, Gel; D004926:Escherichia coli; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D007939:Leukemia L1210 / Q000378:metabolism*; D008025:Ligases / Q000378:metabolism; D008214:Lymphocytes / Q000378:metabolism*; D008745:Methylation; D051379:Mice; D008854:Microscopy, Electron; D012329:RNA, Bacterial / Q000378:metabolism; D012334:RNA, Neoplasm / Q000378:metabolism; D012343:RNA, Transfer / Q000378:metabolism*; D014166:Transferases / Q000378:metabolism
chemical_list: D002247:Carbon Isotopes; D012329:RNA, Bacterial; D012334:RNA, Neoplasm; D012343:RNA, Transfer; D014166:Transferases; D008025:Ligases