Methylmalonic aciduria and homocystinuria type C protein (MMACHC) is a protein that in humans is encoded by the MMACHC gene.
Function
The C-terminal region of the product of the MMACHC gene is similar to TonB, a bacterial protein involved in energy transduction for cobalamin uptake. The MMACHC gene product catalyzes the decyanation of cyanocobalamin as well as the dealkylation of alkylcobalamins including methylcobalamin and adenosylcobalamin.Luciana Hannibal, Jihoe Kim, Nicola E. Brasch, Sihe Wang, David S. Rosenblatt, Ruma Banerjee, and Donald W. Jacobsen (August 2009). "Processing of alkylcobalamins in mammalian cells: a role for the MMACHC (cblC) gene product". Mol Genet Metab. 2009 Aug; 97(4): 260–266. The MMACHC gene product is characterised as a cyanocobalamin reductase (cyanide-eliminating) and a alkylcobalamin reductase. It enables the interconversion of cyano- and alkylcobalamins.Quadros EV, Jackson B, Hoffbrand AV, Linnell JC. "Interconversion of cobalamins in human lymphocytes in vitro and the influence of nitrous oxide on the synthesis of cobalamin coenzymes". Vitamin B12, Proceedings of the Third European Symposium on Vitamin B12 and Intrinsic Factor. 1979;1045-1054.Quadros, EV. "Advances in the Understanding of Cobalamin Assimilation and Metabolism". Br J Haematol. 2010 Jan; 148(2): 195–204.
Clinical significance
Mutations are associated with combined homocystinuria and methylmalonic acidemia.
References
Further reading
External links GeneReviews/NCBI/NIH/UW entry on Disorders of Intracellular Cobalamin Metabolism