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

FEBS Letters

Nachmias, Vivianne T.²  Barron-Casella, Emily¹  Casella, James F.¹  Golla, Rajasree² 

[1] Department of Pediatrics, Division of Hematology, Johns Hopkins University, Baltimore, MD, USA;Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6058, USA

关键词: Blood platelet;    Cytoskeleton;    Cap Z;    Capping protein;    Thrombin activation;    2-D electrophoresis;    CSK;    cytoskeleton;    HSP;    high-speed pellet;    HSS;    highspeed supernatant;    WPL;    whole-platelet lysate;    Tβ 4;    thymosin beta four;   

DOI  :  10.1016/0014-5793(95)01474-8

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

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.

【 授权许可】

Unknown