Figure 1.

Ct-RSF is restricted to the nucleus and colocalizes with the SR protein hrp45 in nuclear speckles. (A) C. tentans diploid cells were stained with anti-Ct-RSF and anti-hrp45 antibodies. In cells grown in normal medium (top), the staining patterns for the two proteins overlapped extensively. In cells treated with actinomycin D (bottom), both Ct-RSF and hrp45 were redistributed into the same larger and more intensively stained speckles. (B) Ct-RSF and hrp45 were restricted to the nucleus and shifted into large speckles also upon treatment with DRB and cycloheximide. In contrast, the hnRNP protein hrp36 did not accumulate in the same speckles. To some extent, it accumulated in the cytoplasm. Bars, 2 μm.