FIG. 3.

SUMO modification of the hnRNP M and C proteins does not significantly disrupt immunopurified hnRNP complexes. hnRNP complexes were immunopurified from the [³⁵S]methionine-labeled HeLa cell nucleoplasm and incubated with SUMO E1 and E2 conjugating enzymes in the presence (bottom panel) and in the absence (top panel) of ATP. Reactions were resolved by two-dimensional gel electrophoresis. Individual hnRNPs are labeled according to the method of Piñol-Roma et al. (31). Molecular mass markers are indicated on the left.