Sea urchin egg villin: Identification of villin in a non-epithelial cell from an invertebrate species

F. S. Wang, E. M. Bonder

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


Fertilization of sea urchin eggs results in the rapid polymerization of actin filaments and subsequent formation of a brush border-like cortical cytoskeleton. A 110 x 103M(r) (110K) actin binding protein has been purified from extracts of unfertilized Strongylocentrotus purpuratus eggs. Analysis of polymeriz ation kinetics using fluorescence and viscometry assays demonstrated that 110K accelerated the nucleation phase of actin assembly only in the presence of elevated Ca2+. The C2+-mediated effects were correlated with a decrease in sedimentable polymer and a decrease in average filament length. Addition of Ca2+ to solutions of 110K and F actin, polymerized in the presence of EGTA, resulted in a precipitous drop in viscosity and the decreased viscosity was fully reversible upon chelation of Ca2+. The Ca2+ threshold for 110K activation was in the 10-6 to 10-7M range. Nucleated assembly experiments using Limulus sperm acrosomal processes demonstrated that egg 110K capped the barbed ends of actin filaments. In the absence of Ca2+, 110K organized actin filaments into bundles at pH values less than 7.4. Anti-egg 110K antibody crossreacted with chicken intestinal epithelial cell villin and anti porcine villin headpiece monoclonal antibody crossreacted with 110K. Further, 110K possesses an ~10 x 103 M(r) terminal polypeptide segment that is immunologically related to villin headpiece. These studies demonstrate that sea urchin egg 110K is functionally, immunologically and structurally related to villin, an actin binding protein expressed in specific epithelial tissues in vertebrates. Consequently, this finding provides insight into the potential mechanisms that might determine the genesis of the cortical brush border cytoarchitecture in sea urchin eggs and further sheds light on the evolution of the villin protein family.

Original languageEnglish (US)
Pages (from-to)61-71
Number of pages11
JournalJournal of cell science
Issue number1
StatePublished - 1991

All Science Journal Classification (ASJC) codes

  • Cell Biology


  • Actin binding protein
  • Sea urchin egg
  • Villin


Dive into the research topics of 'Sea urchin egg villin: Identification of villin in a non-epithelial cell from an invertebrate species'. Together they form a unique fingerprint.

Cite this