Stoichiometry of Sulfolobus Ribosomal-Protein L12e in 50s Subunits Determined by Quantification of Immunoblots

A monoclonal antibody reactive with Sulfolobus solfataricus acidic ribosomal protein SsoL12e was prepared and employed to determine the stoichiometry of this protein in 50S ribosomal subunits by quantification of chloronaphthol-stained protein bands from immunoblots. Approximately four copies of SsoL12e were detected per 50S ribosome. This finding extends previous studies demonstrating the involvement of this protein in a multimeric protein complex in the ribosomal factor binding domain of Sulfolobus and strengthens the concept that this structural motif is a highly conserved and presumably critical feature of the ribosome.