Plk1 negatively regulates PRC1 to prevent premature midzone formation before cytokinesis.

To achieve mitosis and cytokinesis, microtubules must assemble into distinct structures at different stages of cell division-mitotic spindles to segregate the chromosomes before anaphase and midzones to keep sister genomes apart and guide the cleavage furrow after anaphase. This temporal regulation is believed to involve Cdk1 kinase, which is inactivated in a switch-like way after anaphase. We found that inhibiting Plk1 caused premature assembly of midzones in cells still in metaphase, breaking the temporal regulation of microtubules.

Measuring phosphorylation-specific changes in response to kinase inhibitors in mammalian cells using quantitative proteomics.

Many cancers have been associated with the deregulation of kinases, and thus, kinases have become a prime target for the development of cancer treatments. This focus on kinases has resulted in the approval of several small-molecule kinase inhibitors for cancer treatments. Further, the use of these inhibitors as tools to study cancer has provided valuable information about biological mechanisms.

Effect of high-accuracy precursor masses on phosphopeptide identification from MS3 spectra.

This contribution investigates the impact of precursor ion accuracy on the number of phosphopeptides identified from neutral loss-triggered MS(3) spectra acquired on high-accuracy instruments. We show that replacing the MS(3) precursor (parent) ion mass by a highly accurate MS(2) precursor (grandparent) mass increases the number of identified phosphopeptides 3- to 5-fold. The number of unique phosphopeptides identified in addition to the MS(2) data increases from 6% to 24%.

Binding partner switching on microtubules and aurora-B in the mitosis to cytokinesis transition.

The cytoskeleton globally reorganizes between mitosis (M phase) and cytokinesis (C phase), which presumably requires extensive regulatory changes. To reveal these changes, we undertook a comparative proteomics analysis of cells tightly drug-synchronized in each phase. We identified 25 proteins that bind selectively to microtubules in C phase and identified several novel binding partners including nucleolar and spindle-associated protein.

Robust prediction of the MASCOT score for an improved quality assessment in mass spectrometric proteomics.

Protein identification by tandem mass spectrometry is based on the reliable processing of the acquired data. Unfortunately, the generation of a large number of poor quality spectra is commonly observed in LC-MS/MS, and the processing of these mostly noninformative spectra with its associated costs should be avoided. We present a continuous quality score that can be computed very quickly and that can be considered an approximation of the MASCOT score in case of a correct identification.