Define interaction of folate with vitamin B₁₂?

Vitamin B₁₂: For the conversion of folic acid to folinic acid, vitamin B₁₂ is required. Vitamin BIZ deficiency causes a rise in un-conjugated folates and a marked depletion of intracellular conjugated folates. One of the vitamin B₁₂ dependent enzymes, methionine synthase, functions in one of the two folate cycles, namely, the methylation cycle, as you may recall reading earlier. Interruption of the cycle reduces the level of S-adenosylmethionine. Disruption of the methylation cycle also causes lack of DNA biosynthesis and anaemia.