MTR(redirected from Mass Transit Railway)
Also found in: Acronyms.
MTRA gene on chromosome 1q43 that encodes an enzyme which transfers a methyl group from methyl-cobalamin to homocysteine, yielding enzyme-bound cob(I)alamin and methionine. It then remethylates the cofactor using methyltetrahydrofolate.
Defects in MTRR cause methylcobalamin deficiency type E and folate-sensitive neural tube defects.