Dedio J, Müller-Esterl W
Institute for Physiological Chemistry and Pathobiochemistry, Johannes Gutenberg University at Mainz, Germany.
FEBS Lett. 1996 Dec 16;399(3):255-8. doi: 10.1016/s0014-5793(96)01339-7.
The endothelial protein p33/gC1qR is thought to mediate the assembly of components of the kinin-forming and complement-activating pathways on the surface of cardiovascular cells. FACS analysis of intact human umbilical vein endothelial cells using specific antibodies to p33 revealed a minor fluorescence on the cell surface whereas permeabilized cells showed a bright fluorescence indicative of an intracellular localization of p33. Immunostaining of fixed cells confirmed the predominant intracellular localization of p33. Fractionation studies demonstrated that the vesicular but not the membrane fraction of EA.hy926 cells is rich in p33. We conclude that externalization of p33 must precede its complex formation with target proteins on the endothelial cell surface.
内皮蛋白p33/gC1qR被认为可介导激肽形成和补体激活途径的成分在心血管细胞表面的组装。使用针对p33的特异性抗体对完整的人脐静脉内皮细胞进行流式细胞术分析，结果显示细胞表面有微弱荧光，而通透处理的细胞则显示出明亮荧光，表明p33定位于细胞内。固定细胞的免疫染色证实了p33主要定位于细胞内。分级分离研究表明，EA.hy926细胞的囊泡部分而非膜部分富含p33。我们得出结论，p33的外化必定先于其在内皮细胞表面与靶蛋白形成复合物。
