Crystal structure of the armadillo repeat domain of adenomatous polyposis coli which reveals its inherent flexibility

► Here we report the crystal structure of the ARM domain (residues 407-775) of APC. ► Seven armadillo repeats fold into a compact domain, with Arm2/5 showing deviations. ► A groove on APC-ARM might be the recognition site for APC-binding partners. ► Structural comparison reveals that APC-ARM has an intrinsic flexibility. ► The intrinsic flexibility might be an inherent property for ARM domains in general.