title: Heterogeneity of native ribosomal 60-S subunits in Ehrlich ascites tumor cells cultured in vitro.
abstract: Native large ribosomal subunits in cultured Ehrlich ascites tumor cells analyzed by high-resolution CsCl isopycnic centrifugation consist of at least two classes of particles with densities of 1.57 g/cm3 (LI) and 1.59 g/cm3 (LII), respectively. A wash with 0.5 M KCl converts LI into particles with the density of LII particles. Incubation of derived large subunits (density 1.59 g/cm3) with 0.5 M KCl wash of reticulocyte ribosomes leads to the formation of particles with the density of LI particles. A protein with a molecular weight of 57000 present in the high-KCl wash of 60-S native subunits was virtually absent in the KCl wash of 40-S subunits or polyribosomes suggesting that specific protein factors may be present on some native 60-S subunits. Possible functions of these protein factors are discussed.
mesh_terms: D000818:Animals; D002286:Carcinoma, Ehrlich Tumor / Q000378:metabolism / Q000648:ultrastructure*; D002458:Cell Fractionation; D002478:Cells, Cultured; D002499:Centrifugation, Density Gradient; D004591:Electrophoresis, Polyacrylamide Gel; D008970:Molecular Weight; D011132:Polyribosomes / Q000648:ultrastructure; D011485:Protein Binding; D012269:Ribosomal Proteins / Q000032:analysis / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism / Q000648:ultrastructure*
chemical_list: D012269:Ribosomal Proteins