Source was cell extract of S2 cell line; bait produced from transfected construct; prey produced from transfected construct.

smt3 (SUMO) is covalently linked to ird5 but not key.

ird5 sumoylation is stimulated by immune challenge.

smt3-bound ird5 protein migrates with a higher apparent molecular weight that is consistent with monosuloylation.

S2 cells were treated with heat-killed E. coli to stimulate an immune response. smt3 was affinity purified on a nickel column under denaturing conditions such that only covalently bound (sumoylated) proteins should be co-purified.