Identifying the Trigger of c-IAPs: Structural and Functional Characterization of CARD-Mediated Modulation of Ubiquitin Ligase Activity

In this issue of Molecular Cell , Lopez et al. (2011) examine the caspase-recruitment domain (CARD) of c-IAP1 to reveal an intriguing mechanism in which conformational changes of the CARD determine c-IAP1's ubiquitin ligase activity, with implications for regulation of cell proliferation and survival by the IAPs.