Tracking down the ZP domain: From the mammalian zona pellucida to the molluscan vitelline envelope

Semin Reprod Med. 2006 Sep;24(4):204-16. doi: 10.1055/s-2006-948550.


Oocytes from virtually all organisms are surrounded by at least one coat. This specialized extracellular matrix, called the zona pellucida (ZP) in mammals and the vitelline envelope (VE) in nonmammals, has a structural function and plays essential roles in oogenesis, fertilization, and early development. During the last 15 years, compelling evidence has accumulated that all ZP/VE subunits polymerize using a conserved sequence, the ZP domain, so that the basic structural features of egg coat matrices have been maintained through evolution. Moreover, ZP domains have been identified in many other polymeric extracellular proteins from eukaryotes. This review compares the ultrastructure and molecular composition of egg coats from mollusc to human, suggests a common mechanism for assembly of ZP/VE proteins, and discusses alternative models of how these could be arranged within filaments.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Egg Proteins / chemistry*
  • Egg Proteins / genetics
  • Egg Proteins / metabolism
  • Egg Proteins / ultrastructure
  • Female
  • Mammals
  • Models, Biological
  • Mollusca
  • Ovum / chemistry*
  • Ovum / metabolism
  • Protein Structure, Tertiary
  • Sperm-Ovum Interactions
  • Vitelline Membrane / chemistry*
  • Vitelline Membrane / ultrastructure
  • Zona Pellucida / chemistry*
  • Zona Pellucida / ultrastructure


  • Egg Proteins