Abstract
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 language | English (US) |
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Pages (from-to) | 258-262 |
Number of pages | 5 |
Journal | FEBS Letters |
Volume | 378 |
Issue number | 3 |
DOIs | |
State | Published - Jan 15 1996 |
Keywords
- 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