Fig. 7. Ct-eIF4H cannot be immunoprecipitated together with proteins present in pre-mRNP and mRNP complexes in the nucleus. Nuclear extracts (NE) from C. tentans tissue culture cells were immunoprecipitated with antibodies directed against either Ct-eIF4H (A) or the nuclear mRNP protein hrp23 (B). Immunoprecipitated (IP) complexes were analyzed by western blotting. Anti-Ct-eIF4H antibodies precipitated Ct-eIF4H, but not hrp23 and hrp45 (both are known to be associated with pre-mRNPs in the nucleus) or CBP20. Anti-hrp23 antibodies precipitated hrp23, hrp45 and CBP20 but not Ct-eIF4H.