With the development of systems biology projects aimed at modeling the cell, accurate and absolute measurements of cellular protein concentrations are increasingly important. However, methods for absolute quantification at the proteomic level remain rare. Using the yeast Saccharomyces cerevisiae, we propose a new method based on the radioactive labeling with an (35)S compound and 2-D PAGE. The principle is simple: cells are grown for more than four generations in the presence of a unique sulfur source labeled at a defined specific radioactivity, ensuring that more than 90% of the proteins are labeled at the same specific radioactivity as the sulfur source. After separation of (35)S-labeled proteins on 2-D gels, each protein is counted. The amount of each protein present in the gel is then calculated, from which is deduced the amount of each protein per cell. The method, limited to soluble and abundant proteins visible on 2-D gels, is simple, precise and reproducible and does not require an internal standard. We use it to compare the amounts of proteins in two growth conditions: 100 muM sulfate or 500 muM methionine. Up to now, we only had transcriptional data on the expression of these proteins in both conditions.
|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|