Fig. 4.

Ultrastructural identification of cytoplasmic snRNP bodies. a Immunogold labeling of Sm proteins (mAb Y12). Two cytoplasmic bodies (CsB) in close contact (arrows) with a large accumulation of Sm proteins were observed occasionally. In the cytoplasm, the signal was more scattered than in the CsB. b m3G snRNA. snRNA is preferentially localized in the CsB and in several smaller clusters in the cytoplasm (dashed line). c Colocalization of U2 snRNA (10 nm) and Sm proteins (15 nm) immunogold/high resolution ISH method. U2 and Sm can be localized in various zones of the bodies. In the nucleoplasm, the majority of Sm protein clusters also contained the U2 snRNA (arrowheads). Sometimes, the Sm proteins (asterisk) were observed alone. Bars 0.5 μm