methionine synthase reductase, mitochondrial (MSR, MTRR)

Function

• role in reductive regeneration of cob(I)alamin cofactor required for the maintenance of methionine synthase in a functional state

2 [methionine synthase]-methylcob(I)alamin +
2 S-adenosylhomocysteine + NADP+
        <-->
2 [methionine synthase]-cob(II)alamin + NADPH +
2 S-adenosyl-L-methionine

Cofactor: FAD, FMN

Structure

• contains 1 flavodoxin-like domain

Compartment

• isoforms B & C: cytoplasm
• isoform A: mitochondrion

Alternative splicing

named isoforms=3

Expression

• found in all tissues tested
• particularly abundant in skeletal muscle

Pathology

• defects in MTRR are the cause of methylcobalamin deficiency type E

Polymorphism

• variant Met-49 has been associated with an increased risk for spina bifida & may be associated with chromosomal non- disjunction & Down syndrome

More general terms

• oxidoreductase
• flavoprotein
• mitochondrial protein

Database

• OMIM: https://mirror.omim.org/entry/236270
• OMIM: https://mirror.omim.org/entry/602568
• UniProt: http://www.uniprot.org/uniprot/Q9UBK8.html