FIG. 4.
hnRNP C1 contains two SUMO modification consensus sequences and can be expressed and modified by SUMO in vitro. (A) A schematic representation of the hnRNP C1 protein structure is depicted. SUMO modification consensus sequences surrounding lysines 184 and 237 are indicated. RBD, RNA-binding domain; CID, C-protein interaction domain. (B) hnRNP C1 was translated in rabbit reticulocyte lysate in the presence of [35S]methionine (lane 1) and incubated with SUMO E1 and E2 conjugating enzymes either in the absence of exogenously added SUMO-1 (lane 2) or in the presence of His-tagged SUMO-1 (lane 3) or GST-tagged SUMO-1 (lane 4). Reactions were separated by SDS-PAGE and analyzed by autoradiography. Molecular mass standards are indicated on the left. Unmodified hnRNP C1, His-SUMO-modified hnRNP C1, and GST-SUMO-modified hnRNP C1 are indicated on the right.