Internalization of plasma membrane Ca2+-ATPase during Xenopus oocyte maturation

Dev Biol. 2008 Dec 1;324(1):99-107. doi: 10.1016/j.ydbio.2008.09.007. Epub 2008 Sep 18.


A transient increase in intracellular Ca(2+) is the universal signal for egg activation at fertilization. Eggs acquire the ability to mount the specialized fertilization-specific Ca(2+) signal during oocyte maturation. The first Ca(2+) transient following sperm entry in vertebrate eggs has a slow rising phase followed by a sustained plateau. The molecular determinants of the sustained plateau are poorly understood. We have recently shown that a critical determinant of Ca(2+) signaling differentiation during oocyte maturation is internalization of the plasma membrane calcium ATPase (PMCA). PMCA internalization is representative of endocytosis of several integral membrane proteins during oocyte maturation, a requisite process for early embryogenesis. Here we investigate the mechanisms regulating PMCA internalization. To track PMCA trafficking in live cells we cloned a full-length cDNA of Xenopus PMCA1, and show that GFP-tagged PMCA traffics in a similar fashion to endogenous PMCA. Functional data show that MPF activation during oocyte maturation is required for full PMCA internalization. Pharmacological and co-localization studies argue that PMCA is internalized through a lipid raft endocytic pathway. Deletion analysis reveal a requirement for the N-terminal cytoplasmic domain for efficient internalization. Together these studies define the mechanistic requirements for PMCA internalization during oocyte maturation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Calcium Signaling / physiology*
  • Cell Membrane / metabolism
  • Endocytosis
  • Female
  • Molecular Sequence Data
  • Oocytes / physiology*
  • Oogenesis
  • Plasma Membrane Calcium-Transporting ATPases / genetics
  • Plasma Membrane Calcium-Transporting ATPases / physiology*
  • Protein Structure, Tertiary
  • Protein Transport
  • Xenopus Proteins / genetics
  • Xenopus Proteins / metabolism
  • Xenopus laevis / embryology
  • Xenopus laevis / physiology*


  • Xenopus Proteins
  • Plasma Membrane Calcium-Transporting ATPases