title: The effect of sodium chloride on the structure of ribonucleoprotein particles from rat liver nuclei.
abstract: 38S (monoparticles) and greater than 50--200S ribonucleoprotein particles (polyparticles) from rat liver nuclei were treated with increasing concentrations of sodium chloride. Treatment of 38S or greater than 50--200S particles, with 0.14, 0.25, 0.5, 1.0, and 2.0M NaCl resulted in a decrease of protein to RNA ratios from 8 to 3.1 for 38S particles and from 4.0 to 1.5 for greater than 20--200S particles. Correspondingly the densities in CsCl increased. Whereas the maximum of the sedimentation profile of polyparticles decreased from 90S to 50S after treatment with increasing NaCl concentrations, a discontinuous change was found in the case of monoparticles. It was shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis that the proteins which were dissociated by NaCl were in the molecular weight range of 30--45 000. Four of the 5 small molecular weight RNAs in the range of 4.5 to 8S remained tightly associated even after treatment of polyparticles with 2.0M NaCl. When 38S or 70--200S nRNP particles were exposed to increasing concentrations of NaCl (0.25, 0.5, 1.0, 2.0M), the molar ellipticity at 264 nm increased progressively to about 40%. Upon NaCl treatment of polyparticles and successive removal of the dissociated proteins by centrifugation the increase in the positive CD band at 264 nm was only 15%.
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000187:drug effects / Q000648:ultrastructure*; D002499:Centrifugation, Density Gradient; D002942:Circular Dichroism; D008099:Liver / Q000648:ultrastructure*; D008297:Male; D009690:Nucleic Acid Conformation; D009698:Nucleoproteins / Q000032:analysis*; D011487:Protein Conformation; D051381:Rats; D012261:Ribonucleoproteins / Q000032:analysis*; D012965:Sodium Chloride / Q000494:pharmacology*
chemical_list: D009698:Nucleoproteins; D012261:Ribonucleoproteins; D012965:Sodium Chloride