Significance The proto-oncogene KRAS , a small GTPase, is frequently mutated in pancreatic, colorectal, and lung cancer. These mutations result in elevated levels of the activated guanosine triphosphate-bound form of KRAS. Localized at the plasma membrane, KRAS functions to recruit effectors, predominantly RAF kinase for activation and initiation of the MAPK signaling cascade. Combining computational and biophysical methods we identify a membrane-distal state of the KRAS G-domain that alternates with two previously described membrane-proximal states through dynamic reorganization of the hypervariable region. Comprising about 90% of the ensemble, this membrane-distal state of the G-domain dominates the proximal states and may facilitate KRAS to recruit cytosolic RAF kinase to the membrane by a fly-casting mechanism.