The ribosomal stalk is formed by four acidic phosphoproteins in Saccharomyces cerevisiae, P1a, P1?, P2a and P2?, which form two heterodimers, P1a/P2? and P1?/P2a, that preferentially bind to sites A and B of the P0 protein, respectively. Using mutant strains carrying only one of the four possible P1/P2 combinations, we found a specific phenotype associated to each P1/P2 pair, indicating that not all acidic P proteins play the same role. The absence of one P1/P2 heterodimer reduced the rate of cell growth by varying degrees, depending on the proteins missing. Synthesis of the 60S ribosomal subunit also decreased, particularly in strains carrying the unusual P1a-P2a or P1?-P2? heterodimers, although the distinct P1/P2 dimers are bound with similar affinity to the mutant ribosome. While in wild-type strains the B site bound P1?/P2a in a highly specific manner and the A site bound the four P proteins similarly, both the A and B binding sites efficiently bound practically any P1/P2 pair in mutant strains expressing truncated P0 proteins. The reported results support that while most ribosomes contain a P1a/P2?-P0-P1?/P2a structure in normal conditions, the stalk assembly mechanism can generate alternative compositions, which have been previously detected in the cell.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Reference||Annotation Extension|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Conditions||Strain||Source||Reference|