Figure 2: The nuclear SMN complexes isolated contain FOP but not SmB/B’ and SmD. (A) The nuclear SMN complexes were pulled down from the nuclear extract of parental 293TRex cells or from 293TRex cells expressing HB-SMN-F (HB-SMN-F cells) by biotin affinity method, and analyzed by western blotting with the antibodies indicated at the right. (B) Endogenous SMN complexes were immunoprecipitated from the nuclear extract of 293TRex cells with anti- SMN antibody or control IgG(IgG), and analyzed by western blotting with the antibodies indicated at the right. A staining band corresponding to that of IgG heavy chain is also indicated. (C) SMN complexes were immunoprecipitated with anti-FLAG M2 antibody fixed beads from cytoplasmic or nuclear extract of HB-SMN-F or parental 293TRex cells, and analyzed by western blotting with the antibodies indicated at the right. A staining band corresponding to that of IgG light chain is also indicated. (D) RNAs extracted from the SMN complexes isolated from the nuclear extract of HB-SMN-F cells or 293TRex cells were separated by denaturing urea PAGE and stained with SYBR gold. The RNAs in the staining bands (1-3) are identified by LC-MS/MS-Ariadne analysis, and the identified RNAs are indicated at the right.