Vitamin B12 transporter, ABC-type Enzyme Commission 188.8.131.52 is a translocase for “cobalamin” (vitamin B12). The translocase is shown in the diagram above, and as ABC-type converts ATP into ADP energetically to bring vitamin B12 into cells. Cobalamin is a cobalt containing molecule of complex structure, and is shown below. Vitamin B12 in humans is essential to all 211 human cell types. Cobalamin is a coenzyme in both amino-acid and fatty-acid metabolism.