p97 belongs to the superfamily of AAA+ ATPases and is characterized by a tandem AAA module， an N-terminal domain involved in substrate and cofactor interactions， and a functionally important unstructured C-terminal tail. The ATPase activity is controlled by an intradomain communication within the same protomer and an interdomain communication between neighboring protomers. Here， we present for the first time crystal structures in which the physiologically relevant p97 hexamer constitutes the content of the asymmetric unit， namely in the apo state without nucleotide in either the D1 or D2 module and in the pre-activated state with ATPγS bound to both modules. The structures provide new mechanistic insights into the interdomain communication mediated by conformational changes of the C terminus as well as an intersubunit signaling network， which couples the nucleotide state to the conformation of the central putative substrate binding pore.