FIG. 1.

Immunopurification of complexes containing hnRNP proteins from different subcellular fractions. (A) HeLa cells were labeled with [³⁵S]methionine and fractionated as described in the text. Immunopurifications were carried out from each fraction with monoclonal antibodies to hnRNP A1 (4B10) or hnRNP C1/C2 (4F4) or nonimmune parent myeloma immunoglobulins (SP2/0). The positions of hnRNP A1 and hnRNP C1/C2 in the gel are indicated on the right. The asterisk indicates the 130-kDa protein discussed in the text. Cyto., cytosol; Triton, Triton-extracted fraction; Nup., nucleoplasmic fraction. (B) Immunopurifications carried out under conditions identical to those shown in panel A, using monoclonal antibodies to hnRNP K/J (12G4) and hnRNP U (3G6). The positions of hnRNP K/J and hnRNP U in the gel are indicated on the right. Positions of molecular mass standards (in kilodaltons) are indicated on the left.