Isolation and characterization of sea urchin egg spectrin: calcium modulation of the spectrin-actin interaction

Cell Motil Cytoskeleton. 1987;7(4):304-14. doi: 10.1002/cm.970070403.


Sea urchin egg spectrin has been purified from a homogenate of unfertilized Strongylocentrotus purpuratus eggs using standard biochemical procedures. SDS-PAGE analysis of the molecule revealed a closely spaced, high molecular weight doublet at 237/234 kDa (present in an equimolar ratio). Rotary shadowed images of egg spectrin revealed a double-stranded, elongate, flexible rod-shaped contour, measuring 210 nm in length and approximately 4-8 nm in width. Additionally, this molecule is shown to be immunologically related to avian erythroid spectrin, since it crossreacts with antibodies prepared against the chicken erythrocyte alpha-spectrin/240 kDa subunit. The interaction of egg spectrin with actin was examined by sedimentation and falling-ball viscometry assays. The binding and cross linking properties of spectrin to actin demonstrate a unique Ca++-sensitive regulation at micromolar Ca++ concentrations. This observation provides new insight into the way Ca++ may regulate spectrin-actin interactions in vitro and further suggests possible structural and modulatory roles for egg spectrin in the developing sea urchin embryo.

Publication types

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

MeSH terms

  • Actins / metabolism*
  • Animals
  • Calcium / pharmacology*
  • Cytoskeleton / metabolism
  • Female
  • Molecular Weight
  • Ovum / metabolism*
  • Sea Urchins
  • Spectrin / isolation & purification
  • Spectrin / metabolism*
  • Viscosity


  • Actins
  • Spectrin
  • Calcium