Comparison of large fragments obtained by T 1 RNase digestion of ribosomal and nucleolar preribosomal RNA of novikoff hepatoma ascites cells: The 5′-terminal eicosanucleotide

Abstract

Summary Large T 1 RNase fragments of 18S and 28S rRNA and their nucleolar precursors were separated by successive elution from columns of DEAE Sephadex at pH 7.6 and DEAE-cellulose at pH 3.4, respectively. The fragments that contain the methylated oligonucleotides Am-Gm-Cm-Ap, Um-Gm-Up, Gm-Up and Cm-Ap are referred to as α2 −2 , α2 −4 , α2 −3 and α1 −1 ′. Fragment α2 −2 is the eicosanucleotide Am-Gm-Cm-A-A-A-U-U-C-A-U-A-U-U-C-A-A-A-C-Gp which is the 5′ end of 28S rRNA and its precursors including nucleolar 45S RNA. The dinucleotide Cm-Ap is present only in 18S rRNA and 45S nucleolar RNA.