Regulators of apoptosis are thought to work in concert, but the molecular interactions of this
process are not understood. Here, we show that in response to cell death stimulation,
survivin, a member of the inhibitor of apoptosis (IAP) gene family, associates with another
IAP protein, XIAP, via conserved baculovirus IAP repeats. Formation of a survivin-XIAP
complex promotes increased XIAP stability against ubiquitination/proteasomal destruction
and synergistic inhibition of apoptosis, which is abolished in XIAP–/–cells. Therefore …