title: Involvement of 30S ribosomal protein S1 in poly(U)-directed polyphenylalanine synthesis.
abstract: The effect of 30S ribosomal protein S1 on poly(U)-directed polyphenylalanine synthesis was studied using a highly purified cell-free system which was devoid of endogenous S1. The system consisted of homogeneous preparations of EF-Tu, EF-Ts, and EF-G, and 70S ribosomes from which protein S1 had been removed by poly(U)-cellulose column chromatography. It was found that protein S1 was indispensable for translation of poly(U) by an S1-depleted system at low concentrations of poly(U). On the other hand, at higher concentrations of poly(U), a considerable amount of polyphenylalanine was synthesized in the absence of added S1. The stimulatory effect of S1 was observed at all Mg2+ concentrations examined but was most pronounced at 10 mM Mg2+. Some physicochemical properties of the protein were also studied. It was demonstrated that the protein has an elongated shape with an axial ratio of approximately 8.5.
mesh_terms: D004926:Escherichia coli / Q000378:metabolism; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D010452:Peptide Biosynthesis; D010441:Peptide Chain Elongation, Translational / Q000187:drug effects; D010445:Peptide Elongation Factors; D010649:Phenylalanine / Q000378:metabolism; D011072:Poly U; D012269:Ribosomal Proteins / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism
chemical_list: D010445:Peptide Elongation Factors; D012269:Ribosomal Proteins; D011072:Poly U; D010649:Phenylalanine; D008274:Magnesium