This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH=CH group of an acceptor with NAD or NADPH as donor. The systematic name of this enzyme class is precorrin-6B:NADP+ oxidoreductase. Other names in common use include precorrin-6X reductase, precorrin-6Y:NADP+ oxidoreductase and CobK. This enzyme is part of the biosynthetic pathway to cobalamin (vitamin B12) in aerobicbacteria.