Structures of the IKK complex. (a) Domain organizations. (b) Crystal structure of IKKβ dimer. (c) Crystal structure of IKKβ NBD in complex with the N-terminal kinase-binding domain (HLX1) of NEMO. (d) Crystal structure of NEMO HLX2 in complex with vFLIP. (e) Crystal structure of CC2-LZ of NEMO in complex with linear di-Ub. (f) Structure of the NEMO ZF domain. (g) A model of full-length NEMO dimer. Abbreviations: di-Ub, di-ubiquitin; IKK, IκB kinase; NBD, NEMO-binding domain; NEMO, NF-κB essential modulator; ZF, zinc finger.