Figure 2. In vitro SUMO2 modification of APC4.

APC4 is a 808 amino acid protein with two consensus SUMO sites at K772 and K798 (A). Full-length wild-type APC4 (B) or the indicated lysine to alanine substitution mutants (C, D, E) were expressed in rabbit reticulocyte lysate in the presence of [³⁵S]-methionine and incubated for the indicated times in modification reactions containing SUMO E1 and E2 enzymes and SUMO2. Proteins were detected by SDS-PAGE and autoradiography. Asterisks indicate sumoylated forms of APC4. Please note that we have rearranged the panels of Figure 2.