Methylmalonic aciduria type A homolog, mitochondrial (Mmaa)

GTPase, binds and hydrolyzes GTP. Involved in intracellular vitamin B12 metabolism, mediates the transport of cobalamin (Cbl) into mitochondria for the final steps of adenosylcobalamin (AdoCbl) synthesis.

Functions as a G-protein chaperone that assists AdoCbl cofactor delivery from MMAB into the methylmalonyl-CoA mutase (MUT) and reactivation of the enzyme during catalysis. .