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

Authors:
Publisher website
Google Scholar
Abstract
Ubiquitin, an important post-translational modification that regulates a variety of biological processes is found in free and conjugated (monoubiquitin and polyubiquitin) forms in the cell. A method for precisely measuring these cellular pools using protein standard absolute quantification mass spectrometry is described; the approach should yield insights into ubiquitin signaling. 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.

This publication has 30 references indexed in Scilit: