PHF8 and TIP60 form a tripartite complex with the splicing factor PSF and associates with newly transcribed nascent RNA. A, A maximum intensity projection of a 3D STORM image of an activated hippocampal neuronal nucleus. Single-molecule imaging of endogenous PHF8 (green), endogenous TIP60 (red), and PTB-associated splicing factor (blue), with the corresponding single-channel views. Each dot corresponds to the localization of a single molecule. Scale bar, 500 nm. B, C, Four representative higher magnification views of the neuronal nucleus depicted in A, showing that PSF (blue) forms a tailing structure within the interface between PHF8 (green) and TIP60 (red) viewed axially B or longitudinally C as a recognizable tripartite complex. Scale bar, 50 nm.