Proteomics of phosphorylation and protein dynamics during fertilization and meiotic exit in the Xenopus egg

Marc Presler, Elizabeth Van Itallie, Allon M. Klein, Ryan Kunz, Margaret L. Coughlin, Leonid Peshkin, Steven P. Gygi, Martin Wühr, Marc W. Kirschner

Research output: Contribution to journalArticle

22 Scopus citations

Abstract

Fertilization releases the meiotic arrest and initiates the events that prepare the egg for the ensuing developmental program. Protein degradation and phosphorylation are known to regulate protein activity during this process. However, the full extent of protein loss and phosphoregulation is still unknown. We examined absolute protein and phosphosite dynamics of the fertilization response by mass spectrometry-based proteomics in electroactivated eggs. To do this, we developed an approach for calculating the stoichiometry of phosphosites from multiplexed proteomics that is compatible with dynamic, stable, and multisite phosphorylation. Overall, the data suggest that degradation is limited to a few low-abundance proteins. However, this degradation promotes extensive dephosphorylation that occurs over a wide range of abundances during meiotic exit. We also show that eggs release a large amount of protein into the medium just after fertilization, most likely related to the blocks to polyspermy. Concomitantly, there is a substantial increase in phosphorylation likely tied to calcium-activated kinases. We identify putative degradation targets and components of the slow block to polyspermy. The analytical approaches demonstrated here are broadly applicable to studies of dynamic biological systems.

Original languageEnglish (US)
Pages (from-to)E10838-E10847
JournalProceedings of the National Academy of Sciences of the United States of America
Volume114
Issue number50
DOIs
StatePublished - Dec 12 2017

All Science Journal Classification (ASJC) codes

  • General

Keywords

  • Cell cycle
  • Confidence intervals
  • Polyspermy block
  • Stoichiometry
  • TMT

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