Recombinant human KRAS (GTPase), isoform b, encompassing amino acids 2-185. This construct contains an N-terminal His-tag (6xHis). The protein also contains the mutation of interest G12V. The protein (BPS Bioscience #100480) was affinity purified and loaded with GppNHp, a non-hydrolyzable GTP analog. Unbound GppNHp was removed by spin column.