Small GTP-binding protein RalA associates with Weibel-Palade bodies in endothelial cells

被引:35
作者
de Leeuw, HPJC [1 ]
Wijers-Koster, PM [1 ]
van Mourik, JA [1 ]
Voorberg, J [1 ]
机构
[1] CLB, Dept Blood Coagulat, NL-1066 CX Amsterdam, Netherlands
关键词
Weibel-Palade bodies; RalA; GTP; von Willebrand factor; endothelial cells;
D O I
10.1055/s-0037-1614349
中图分类号
R5 [内科学];
学科分类号
1002 ; 100201 ;
摘要
In endothelial cells von Willebrand factor (vWF) and P-selectin are stored in dense granules, so-called Weibel-Palade bodies. Upon stimulation of endothelial cells with a variety of agents including thrombin, these organelles fuse with the plasma membrane and release their content. Small GTP-binding proteins have been shown to control release from intracellular storage pools in a number of cells. In this study we have investigated whether small GTP-binding proteins are associated with Weibel-Palade bodies. We isolated Weibel-Palade bodies by centrifugation on two consecutive density gradients of Percoll. The dense fraction in which these subcellular organelles were highly enriched, was analysed by SDS-PAGE followed by GTP overlay. A distinct band with an apparent molecular weight of 28,000 was observed. Two-dimensional gel electrophoresis followed by GTP overlay revealed the presence of a single small GTP-binding protein with an isoelectric point of 7.1. A monoclonal antibody directed against RalA showed reactivity with the small GTP-binding protein present in subcellular fractions that contain Weibel-Palade bodies. The small GTPase RalA was previously identified on dense granules of platelets and on synaptic vesicles in nerve terminals. Our observations suggest that RalA serves a role in regulated exocytosis of Weibel-Palade bodies in endothelial cells.
引用
收藏
页码:1177 / 1181
页数:5
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