Transiently expressed Smac56 homodimerizes and heterodimerizes with Smac60, but not with Smacδ.

<p>Cells were transiently cotransfected with the Ub-Smac56 or Ub-Smacδ with a C-terminal GST tag (pGFLEX) and with full-length Smac^1-239, Ub-Smac56, Ub-Smac60, Ub-Smacδ, or ^G76VUb-Smac56 with a C-terminal V5 tag (pcDNA3.1-HA-Ub-Smac-V5), as indicated. Cells were lysed, and proteins were purified using GSH-agarose. Lysate proteins (<i>Input</i>) and proteins eluted from the GSH-agarose (<i>Pulldown</i>) were resolved by SDS-PAGE and subjected to western blot analysis with antibody to GST-pi and to the V5 tag.