Analyses of 40S and 60S Ribosomal Proteins of Artemia salina with Two- or “Three-Dimensional” Acrylamide Gel Electrophoresis and Comparisons with Rat Liver 40S and 60S Proteins1
Basic proteins of 40S and 60S subunits of Artemia salina and rat liver were analyzed using two different systems of two-dimensional acrylamide gel electrophoresis. In system I, the first dimension was run at pH 8.6 and the 2nd at pH 4.9, and in system II, the first was run at pH 8.6 and the 2nd in the presence of SDS. “Three-dimensional” electrophoresis was further used for the identification of individual ribosomal proteins. 1. Artemia salina 40S proteins were separated into 27 proteins by “three-dimensional” gel electrophoresis. Their two-dimensional electrophoretogram in system I was somewhat different from that of liver 40S subunits, especially in the less basic region near the origin. Individual Artemia salina 40S proteins were designated according to their correspondence to 40S proteins of rat liver. The proteins S8 or S9 of both subunits overlapped between the two species. Proteins corresponding to rat liver S3b, S5a, and S5 proteins were not detected in Artemia salina 40S proteins. Forty-S proteins of Artemia salina and rat liver were further analyzed by two-dimensional gel electrophoresis in system Il. S7, S9, and S29 proteins overlapped between the two species. Thus, S9 protein may have been almost completely conserved during evolution. 2. Thirty-eight proteins were identified in Artemia salina 60S proteins by “three-dimensional” electrophoresis. The pattern was different from that of rat liver, especially in the basic region on two-dimensional gels in systems I and II. Although the correspondence of individual proteins between the two species was very difficult to find, we designated Artemia salina 60S proteins by considering the mutual relationship to rat liver 60S proteins on the gel. L5, L31, L18, and L18a proteins of Artemia salina appeared to shift to more acidic regions as compared with corresponding 60S proteins of rat liver. 3. The number averages of molecular weights of 40S proteins were 18, 600 for Artemia salina (27 proteins) and 18, 500 for rat liver (29 proteins). Those of 60S proteins were 21, 600 for Artemia salina (38 proteins) 21, 800 for rat liver (38 proteins). The averages of relative basicities of 40S proteins were similar in both species, whereas the average of those of 60S proteins of Artemia salina was lower than that of rat liver 60S proteins. 4. The protein moiety of 40S ribosomes has been conserved more than that of 60S ribosomes during the evolution of animal species.