argK (Escherichia coli K12): Membrane ATPase/protein kinase; Binds and hydrolyzes GTP. Likely functions as a G-protein chaperone that assists AdoCbl cofactor delivery to the methylmalonyl-CoA mutase (MCM) ScpA and reactivation of the enzyme during catalysis; Belongs to the SIMIBI class G3E GTPase family. ArgK/MeaB subfamily.