In enzymology, a vitamin B<sub>12</sub>-transporting ATPase () is an enzyme that catalyzes the chemical reaction
The 3 substrates of this enzyme are ATP, H<sub>2</sub>O, and vitamin B<sub>12</sub>, whereas its 3 products are ADP, phosphate, and vitamin B<sub>12</sub>.
This enzyme belongs to the family of hydrolases, specifically those acting on acid anhydrides to catalyse transmembrane movement of substances. The systematic name of this enzyme class is ATP phosphohydrolase (vitamin B<sub>12</sub>-importing). This enzyme participates in abc transporters - general.
As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes and .