Fig. 4.

AKIP1 is a nuclear protein that is present as speckles. (A) Staining of endogenous AKIP1 with anti-AKIP1 antibody revealed a distinct punctuate staining in the nucleus of HeLa and Hs 578 Bst cells. This punctuate staining was abolished with preincubation with GST-AKIP^* in Hs 578 Bst cells. Staining with secondary antibody alone (donkey anti-rabbit FITC) was used as a control. (Inset) A longer exposure. (B) YFP and FLAG-tagged AKIP1a, AKIP1b, and RR14,15AA AKIP1a were expressed in HeLa cells and visualized by epifluorescence microscopy. AKIP1a and AKIP1b localized to the nucleus, whereas the NLS mutants were diffused throughout the cell.