title: Turnover of HeLa ribosomal RNA. The characterization of a class of RNA in HeLa cytoplasm derived from 28S RNA.
abstract: A class of RNA in HeLa cytoplasm with a sedimentation value of 22S is described. This RNA is a true cytoplasmic component and is not an artifact of cell rupture or of the method of RNA preparation. The 22S RNA sediments in a sucrose gradient with those ribosomal structures containing 28S ribosomal RNA (60S and 74S particles and polyribosomes). It has a base composition and methyl content similar to those of 28S RNA. The kinetics of formation of 22S suggest that it is not a direct product of transcription but is derived in vivo from "old" molecules of 28S RNA.
mesh_terms: D001483:Base Sequence; D002458:Cell Fractionation; D002460:Cell Line; D002501:Centrifugation, Zonal; D003593:Cytoplasm / Q000032:analysis*; D005815:Genetic Code; D006367:HeLa Cells; D007700:Kinetics; D007739:L Cells / Q000032:analysis; D008745:Methylation; D009693:Nucleic Acid Hybridization; D012313:RNA / Q000302:isolation & purification; D012334:RNA, Neoplasm / Q000302:isolation & purification; D012335:RNA, Ribosomal / Q000032:analysis*; D012270:Ribosomes; D014316:Tritium; D014529:Uridine
chemical_list: D012334:RNA, Neoplasm; D012335:RNA, Ribosomal; D014316:Tritium; D012313:RNA; D014529:Uridine