Unusual Features of the Structure of the Major RNA Component of the Larger Subribosomal Particle of the Rabbit Reticulocyte

Abstract

Abstract The major RNA moiety of the larger subribosomal particle of the rabbit reticulocytes was subjected to partial hydrolysis by RNase T 1 . The fragments were separated first by gel filtration and then by zonal centrifugation. The fractions so obtained were analysed for molecular weight, nucleotide composition and for “melting” properties (E vs. temperature). The largest fragments (ca. 400,000 daltons) that were obtained had a high G + C content (ca. 78%). Fragments of this size appear to account for most of ca. 78% G·C basepairs which comprises ca. 40% of the intact molecule. Melting properties of reticulocyte RNA were compared with those of rRNA of the larger subribosomal particle Escherichia coli, Bacillus stearothermophilus and Xenopus laevis. The possible evolutionary significance of the unusual distribution of nucleotides within the polynucleotide chain of the RNA moiety of the larger subribosomal particle of reticulocytes is discussed.