Figure 2. SU(VAR)3–9 and JIL-1 interact in vivo.

(A) Coexpression of JIL-1 and SU(VAR)3–9 in SF9 cells using a baculoviral expression system. left: Western Blot of whole cell Sf9 extract. Proteins were detected using the indicated antibodies. right: Histone methyltransferase assay after co-infection of SF9 cells with flag-JIL-1 and his-SU(VAR)3–9 followed by affinity purification on a Talon™ metal affinity resin. (B) Precipitation of JIL-1 from an SF9 cell extract co-purifies active SU(VAR)3–9. left: Western Blot analysis of flag-coimmunoprecipitations using SF9 whole cell extract after co-infection with the indicated viruses. After the Co-IP flag M2-beads were washed and eluted with the flag peptide. 10% of the eluates were separated by SDS PAGE and analyzed by Western blotting using specific antibodies. right: Histone methyltransferase assay after co-infection of SF9 cells with flag-JIL-1, a flag-JIL^D392A and his-SU(VAR)3–9 followed by affinity purification on a flag M2 affinity resin.