A label free quantitative proteomic analysis of the Saccharomyces cerevisiae nucleus

To gain insight into the nuclear proteome of Saccharomyces cerevisiae, nuclei were isolated and fractionated via sucrose gradient sedimentation. The resulting fractions were analyzed using multidimensional protein identification technology and the detected proteins were quantified using normalized spectral counts. A large number of low abundance proteins, many of which are involved in transcriptional regulation, were recovered. Sucrose gradient elution profiles of known protein complex components demonstrated that this approach may provide insight into the question of what percentage of the total population of a protein is in one complex, versus another protein complex, or exists as a free protein.