Characterization of native 40 S particles from Krebs II mouse ascites tumor cells: resolution, nomenclature and molecular weights of the nonribosomal proteins.

Native 40 S particles from Krebs II mouse ascites tumor cells were isolated on a large scale. A nonribosomal protein moiety of about 30 proteins could be removed from the ribosomal particles by treatment with 250 mM KCl. These proteins were analysed by two-dimensional polyacrylamide gel electrophoresis and turned out to be mostly acidic in nature. The molecular weights of about 17 proteins were determined by three-dimensional gel electrophoresis. Radioactively labelled nonribosomal protein spots were excised from two-dimensional gel electrophoresis. Radioactively labelled nonribosomal protein spots were excised from two-dimensional gels and transferred directly or after electrodialysis onto the third dimension gel. The proteins fell into a molecular weight range from about 20,000 to 300,000.