Prrp and XStau interact with the localization RNP in the cytoplasm. (A) Stage III/IV oocytes were injected with RNA encoding Prrp-myc, and S10 lysates were prepared from isolated nuclear (lane 1 and lanes 3–5) and cytoplasmic (lane 2 and lanes 6–8) fractions. Immunoprecipitations were performed using control antibody plus S10 lysates (lanes 3 and 6), anti-myc in the absence of lysate (lanes 4 and 7), and anti-myc in the presence of nuclear (lane 5) or cytoplasmic (lane 8) lysates. Total (lanes 1 and 2) and immunoprecipitated (lanes 3–8) Vg1 (top) and VegT (bottom) RNAs were detected by RT-PCR. All samples were run on the same gel, but lane order was changed for presentation in the figure. (B) After expression of Prrp-myc in stage III/IV oocytes, immunoprecipitations were performed using control antibody with Prrp-myc cytoplasmic S10 lysate (lane 2), anti-myc alone (lane 3), and anti-myc plus lysate without (lane 4) or with (lane 5) RNase A treatment. Total (lane 1) and bound proteins (lanes 2–5) were separated by 10% SDS-PAGE and were immunoblotted for Vg1RBP/vera (top), hnRNP I (middle), or XStau (bottom). For each panel all samples were run on the same gel, and adjacent lanes are boxed together. (C) Vg1RBP/vera-FLAG was expressed in stage III/IV oocytes and S10 lysates were prepared from isolated nuclear (lanes 1 and 3–5) and cytoplasmic (lanes 2 and 6–8) fractions. Immunoprecipitations were performed using Sepharose beads plus Vg1RBP/vera S10 lysates (lanes 3 and 6), anti-FLAG beads alone (lanes 4 and 7), and anti-FLAG beads in the presence of nuclear (lane 5) or cytoplasmic (lane 8) lysates. Total (lanes 1 and 2) and bound (lanes 3–8) proteins were separated by 10% SDS-PAGE and immunoblotted for XStau. All samples were run on the same gel, with adjacent lanes boxed together for presentation in the figure.