title: The function of ribosomal protein S21 in protein synthesis.
abstract: The function of ribosomal protein S21 in protein synthesis has been examined by (a) inactivation of S21 in situ with specific antibodies and (b) the use of 30-S subunits reconstituted in the absence of S21. The results from the two approaches are consistent, 30-S subunits treated with anti-S21 or lacking S21 are still active in the translation of poly(U) or poly(A, G, U). They are also functional in fMet-tRNA binding when directed by poly(A, G, U) or the AUG triplet. They are not active in the translation of MS2 RNA or Escherichia coli mRNA. The defect of S21-deficient 30-S ribosomes can be traced back to their inability to bind MS2 RNA at the initiation step of protein synthesis. Addition of S21 to S21-deprived subunits restores the MS2-RNA-dependent initiation complex formation.
mesh_terms: D000906:Antibodies / Q000032:analysis; D001426:Bacterial Proteins / Q000096:biosynthesis*; D004926:Escherichia coli / Q000378:metabolism*; D011485:Protein Binding; D014176:Protein Biosynthesis; D012335:RNA, Ribosomal / Q000378:metabolism; D012269:Ribosomal Proteins / Q000276:immunology / Q000502:physiology*
chemical_list: D000906:Antibodies; D001426:Bacterial Proteins; D012335:RNA, Ribosomal; D012269:Ribosomal Proteins; C032643:ribosomal protein S21