FIG. 5.
hnRNP C1 is modified by SUMO at lysine residue 237. Wild-type hnRNP C1 and hnRNP C1 mutants containing lysine-to-arginine substitutions at the two predicted SUMO modification sites (lysines 184 and 237) were translated in rabbit reticulocyte lysate in the presence of [35S]methionine (lanes 1, 3, 5, and 7). The proteins were incubated with SUMO E1 and E2 conjugating enzymes and SUMO-1 (lanes 2, 4, 6, and 8), and their ability to be modified was determined by SDS-PAGE followed by autoradiography. Molecular mass markers are indicated on the left, and unmodified and SUMO-modified hnRNP C1 proteins are indicated on the right.