Human liver ribosomal proteins: Characterization by two-dimensional electrophoresis and molecular weight determinations

Abstract

The proteins of the small (40 S) and large (60 S) ribosomal subunits isolated from normal human liver biopsy specimens, were characterized by comparison of their two-dimensional polyacrylamide gel electrophoresis patterns and molecular weight determinations with those of rat liver ribosomal proteins. Twenty-two and twenty-seven proteins of human liver 40 S and 60 S ribosomal subfractions, respectively, were resolved by two-dimensional electrophoresis. With the exception of small subunit protein S 6 from human liver which had a faster electrophoretic mobility than rat liver S 6 in both dimensions, the fingerprints of ribosomal proteins from human and animal liver are qualitatively and quantitatively very similar. The molecular weights of 25 human liver ribosomal proteins were tested by coelectrophoresis in a “third dimension” with their corresponding proteins of rat liver origin and proved to be identical with the latter when proteins S 6 and L 36 are excluded. It is demonstrated by two-dimensional electrophoresis that structural intact ribosomes can be obtained only from human liver in vivo but not from the postmortal organ.