The 3'-hydroxyl termini in yeast ribosomal RNA.

Abstract

(1) A fraction of high molecular weight RNA was prepared by subjecting total yeast RNA to selective precipitation from aqueous 2.5 M sodium chloride solution at 0°. This "insoluble" RNA accounted for about 80% of the total yeast RNA.(2) The "insoluble" RNA and various of its subfractions obtained by preparative sucrose density-gradient centrifugation were subjected to electrophoretic and end-group analyses.(3) One subfraction, largely composed of 17 S RNA from the smaller ribosomal subunit, was found to contain adenosine as the principal 3′-hydroxyl terminal nucleoside residue. Based on the analysis of 3′-hydroxyl termini, RNA in this subfraction had a mean residue length of about 1600 nucleotides.(4) Another subfraction, largely composed of 26 S RNA from the larger ribosomal subunit, was found to contain uridine as the principal 3′-hydroxyl terminal nucleoside residue. Based on the analysis of 3′-hydroxyl termini, RNA in this subfraction had a mean residue length of about 2400 nucleotides.(5) Electrophoretic and end-group analyses of other subfractions have been reported and discussed in terms of the possible origin of the RNA in these fractions, and also in terms of the way in which the RNA of these fractions might tend to affect the end-group analysis of both the parent fraction and the principal subfractions, which contain RNA from the ribosomal subunits.