Cap Z, a calcium insensitive capping protein in resting and activated platelets

Vivianne T. Nachmias, Rajasree Golla, James F. Casella, Emily Barron-Casella

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


Capping of the barbed-ends of actin filaments is an important mechanism for control of the cytoskeleton. In platelets, a valuable model system, it has been thought that gelsolin was the major capping protein. We now report that platelets contain ~2 μM Cap Z, a calcium insensitive heterodimeric capping protein; two major and additional minor isoforms of both α and β subunits are present. In lysates from resting platelets 75-80% of the Cap Z sediments with the high speed pellet, but if the platelets are activated with thrombin for 10 s, about 15% of the Cap Z leaves the pellet fraction and is found in the high speed supernatant where it is not bound to actin. This translocation of Cap Z to the supernatant is also observed when resting platelets are lysed into buffer containing 50-100 μM GTPγS and 10 mM EGTA. Our results suggest that release of Cap Z from some actin filaments could generate free filament barbed-ends. An increase in free barbed-ends has been reported in platelet lysates prepared shortly after thrombin activation.

Original languageEnglish (US)
Pages (from-to)258-262
Number of pages5
JournalFEBS Letters
Issue number3
StatePublished - Jan 15 1996


  • 2-D electrophoresis
  • Blood platelet
  • Cap Z
  • Capping protein
  • Cytoskeleton
  • Thrombin activation

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology


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