Structural Analysis of Ribosomal 28 S Ribonucleic Acid of Novikoff Hepatoma Cells

The primary sequence of nucleotides was determined for the 99 nucleotide B3-9 subcomponent of 28 S rRNA of Novikoff hepatoma ascites cells; this fragment was purified from the 500 nucleotides GC-rich B3 fragment that is produced by partial cleavage of 28 S rRNA with T1 RNAase. This unique sequence, which is the longest defined thus far for 28 S rRNA, is: see PDF for sequence The only Ap residue is in the 5′-terminal end. The italicized polypyrimidine sequences which have chain lengths of 17, 14, and 21, respectively, are unique markers since they appear only once in 28 S rRNA ot its nucleolar precursors.