Comparison of the subcellular localization of CLP36 and F-actin during various phases of platelet spreading.

Colocalization of F-actin (Ai,Bi, Ci,Di) and CLP36 (Aii-Dii) in early stages (Ai-Bii), and subsequent stages (Ci-ii) of platelet spreading, and after completion of spreading (Di-ii) was revealed by double immunofluorescence staining (merge Ciii,Diii). CLP36 staining of filopods (arrow in Aii) and lamellipods (arrow in Bii) formed during the early phase of spreading is homogenous and accumulates in patches (Cii) or dotted pattern (Dii,Eii) on F-actin–based structures in the late stages of platelet spreading. Note that CLP36 locates to the inner side of the cortical actin-filament belt during the spreading process (Ciii). Double immunofluorescent staining of the focal contact protein vinculin (Ei) and CLP36 (Eii), merge (Eiii); vinculin accumulates in the late stage of spread platelets in patches along circles or spirals at the microfilament tips.40 Bar, 10 μm.