Properties of ribosomal proteins from two mammalian sources

Abstract

Ribosomal protein fractions from rabbit reticulocytes and rat liver were prepared by extracting ribosomes with 0. 2 N-hydrochloric acid or guanidinium chloride and subsequent dialysis. Treatment for 2. 5 hr. or less with 0. 2 N-hydrochloric acid dissolved 46-54% of the proteins, which were richer in arginine and lysine and in N-terminal alanine groups and poorer in aspartic acid and glutamic acid and in N-terminal glycine groups than the acid-insoluble proteins. Protein fractions prepared from the guanidinium chloride extract of ribosomes from rat liver were usually more basic than those from rabbit reticulocytes. The ratios lysine: arginine of fractions in the guanidinium chloride extracts were appreciably higher for proteins from rabbit reticulocytes than from rat liver. The con-centration of urea and the pH of the gel affected the rate of migration and number of bands in starch-gel electrophoresis.