Integration of 18O Labeling and Solution Isoelectric Focusing in a Shotgun Analysis of Mitochondrial Proteins

Forward and reverse 18O labeling are integrated with solution isoelectric focusing and capillary LC-tandem mass spectrometry to evaluate a new strategy for quantitative proteomics, and to study abundance changes in mitochondrial proteins associated with drug resistance in MCF-7 human cancer cells. Galectin-3 binding protein, which is involved in apoptosis, was detected only in the resistant cell line, as a result of reverse labeling. Among 278 proteins identified, twelve were detected with abundances altered at least 2-fold. Keywords comparative proteomics; 18O labeling; reverse labeling; solution isoelectric focusing; galectin; 3 binding protein; human mitochondria; drug resistanc