Protein standard absolute quantification (PSAQ) method for the measurement of cellular ubiquitin pools.

Kaiser, Stephen E; Riley, Brigit E; Shaler, Thomas A; Trevino, R Sean; Becker, Christopher H; Schulman, Howard; Kopito, Ron R

The protein ubiquitin is an important post-translational modifier that regulates a wide variety of biological processes. In cells, ubiquitin is apportioned among distinct pools, which include a variety of free and conjugated species. Although maintenance of a dynamic and complex equilibrium among ubiquitin pools is crucial for cell survival, the tools necessary to quantify each cellular ubiquitin pool have been limited. We have developed a quantitative mass spectrometry approach to measure cellular concentrations of ubiquitin species using isotope-labeled protein standards and applied it to characterize ubiquitin pools in cells and tissues. Our method is convenient, adaptable and should be a valuable tool to facilitate our understanding of this important signaling molecule.

UBIQUITIN; PROTEIN microarrays; MASS spectrometry; IMMUNOGLOBULINS; PEPTIDES

Nature Methods, 2011, Vol 8, Issue 8, p691

1548-7091

Academic Journal

10.1038/nmeth.1649