MMAA

The protein encoded by this gene is involved in the translocation of cobalamin into the mitochondrion, where it is used in the final steps of adenosylcobalamin synthesis. Adenosylcobalamin is a coenzyme required for the activity of methylmalonyl-CoA mutase. Defects in this gene are a cause of methylmalonic aciduria.

Full Name

METHYLMALONIC ACIDURIA (COBALAMIN DEFICIENCY) CBLA TYPE

Function

GTPase, binds and hydrolyzes GTP (PubMed:28497574, PubMed:20876572, PubMed:21138732, PubMed:28943303).

Involved in intracellular vitamin B12 metabolism, mediates the transport of cobalamin (Cbl) into mitochondria for the final steps of adenosylcobalamin (AdoCbl) synthesis (PubMed:28497574, PubMed:20876572).

Functions as a G-protein chaperone that assists AdoCbl cofactor delivery from MMAB to the methylmalonyl-CoA mutase (MMUT) (PubMed:28497574, PubMed:20876572).

Plays a dual role as both a protectase and a reactivase for MMUT (PubMed:21138732, PubMed:28943303).

Protects MMUT from progressive inactivation by oxidation by decreasing the rate of the formation of the oxidized inactive cofactor hydroxocobalamin (OH2Cbl) (PubMed:21138732, PubMed:28943303).

Additionally acts a reactivase by promoting the replacement of OH2Cbl by the active cofactor AdoCbl, restoring the activity of MMUT in the presence and hydrolysis of GTP (PubMed:21138732, PubMed:28943303).

Biological Process

Cobalamin metabolic process Source: MGI

Cellular Location

Cytoplasm
Mitochondrion

Involvement in disease

Methylmalonic aciduria type cblA (MMAA):
A disorder of methylmalonate and cobalamin metabolism due to defective synthesis of adenosylcobalamin.