PAR-3 defines a central subdomain of the cortical actin cap in mouse eggs

Francesca E. Duncan, Stuart B. Moss, Richard M. Schultz, Carmen J. Williams*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

56 Scopus citations


The evolutionarily conserved partitioning defective (PAR) protein PAR-3 is pivotal for establishing and maintaining cell polarity. During mammalian oocyte maturation, the radially symmetric oocyte is transformed into a highly polarized metaphase II (MII)-arrested egg. We therefore examined several aspects of PAR-3 expression during oocyte maturation. We cloned two novel PAR-3 transcripts from an oocyte library that likely encode proteins of Mr = 73 K and 133 K that are phosphorylated during maturation. PAR-3, which is found throughout the GV-intact oocyte, becomes asymmetrically localized during meiosis. Following germinal vesicle breakdown, PAR-3 surrounds the condensing chromosomes and associates with the meiotic spindles. Prior to emission of the first and second polar bodies, PAR-3 is located within a central subdomain of the polarized actin cap, which overlies the spindle. This cortical PAR-3 localization depends on intact microfilaments. These results suggest a role for PAR-3 in establishing asymmetry in the egg and in defining the future site of polar body emission.

Original languageEnglish (US)
Pages (from-to)38-47
Number of pages10
JournalDevelopmental Biology
Issue number1
StatePublished - Apr 1 2005


  • Cortical actin
  • Meiosis
  • Mouse egg
  • PAR-3

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology
  • Cell Biology

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