Effect of PHAX mutant proteins on the distribution of injected U snRNA precursors. (A) Schematic representation of the domain structures of human PHAX protein and the features of the PHAX mutants used in this study. The numbers represent the amino acid numbers of the PHAX protein. WT, wild type. (B) The same mixture of ³²P-labeled RNAs as in Fig. 2 A was injected into the nuclei of Xenopus oocytes either alone (lanes 1–6) or together with 25 ng/oocyte of recombinant PHAXΔCD (ΔCD; lanes 7–9), PHAXΔN (ΔN; lanes 10–12), PHAXΔNES (ΔNES; lanes 13–15), PHAXΔST2 (ΔST2; lanes 16–18), WGA and ΔCD (lanes 19–21), WGA and ΔN (lanes 22–24), WGA and ΔNES (lanes 25–27), or WGA and ΔST2 (lanes 28–30). RNA was analyzed as in Fig. 2 A. (C and D) The ratio of the Nppt signal against the nuclear fraction total signal of U1ΔSm and U5ΔSm, respectively, was calculated from three independent experiments as in A. The means and standard deviations for WGA + ΔCD, WGA + ΔN, WGA + ΔNES, and WGA + ΔST2 are shown. (E) The same RNA mixture was injected with either WGA + ΔCD (lanes 1–9), WGA + ΔN (lanes 10–18), or WGA + ΔNES (lanes 19–27). RNA was analyzed at 0, 1.5, and 3 h as in (A). (F) The distribution of Cy3-labeled m⁷G-capped U1ΔSm RNA was analyzed as in Fig. 1 A at 2 h after microinjection in the presence of WGA + ΔN (right) or WGA + ΔCD (left). C, cytoplasmic fraction. Bars, 20 µm.