Figure 6.

Distribution of the RNA-splicing protein SRm300 in the amine-modified nuclear matrix. SAOS-2 cells, grown on gold grids, were processed by the sulfo-NHS nuclear matrix preparation method for whole-mount EM. The location of a nuclear matrix protein involved in RNA splicing was determined by staining with mAb B4A11 and a 10-nm gold-conjugated second antibody. (a) Low-magnification view of a B4A11-stained cell. The square marks the field selected for the higher magnification whole-mount stereo pair of b. The inset shows the location of SRm300 determined by immunofluorescent staining with mAb B4A11. (b) The dense bodies, corresponding to interchromatin granule clusters (splicing speckles) were heavily stained by mAb B4A11. In contrast, the larger dense bodies corresponding to nucleoli were completely unstained.