NNMT regulates methyl donor metabolism

It’s a common knowledge that excess of NAM gets methylated and many people think that Niacin or Nicotinamide (NAM) will lower methylation potential by spending SAMe. There is even a concept of methyl sink assigned to Niacin.

The article below suggests that NNMT, the enzyme that methylates NAM, may have a second role - interaction with enzymes of the methionine cycle. Specifically it seems to interact with BHMT, AHCY and MAT1A.