Immunochemical evidence of homologies among 50 S ribosomal proteins of Bacillus stearothermophilus and Escherichia coli.

Antibodies prepared against individual 50 S ribosomal subunit proteins from Escherichia coli were reacted with 70 S ribosomal proteins from Bacillus stearothermophilus in order to identify homologous protein pairs. B. stearothermophilus proteins were separated by two-dimensional polyacrylamide gel electrophoresis and transferred electrophoretically to diazobenzyloxymethyl paper to which they became covalently attached. The paper was then washed with antiserum followed by radioactive protein A, and the resulting antigen-antibody-protein A complexes were located by autoradiography. Seventeen cross-reacting protein pairs were identified.