MMACHC reduces Cbl

Stable Identifier
R-HSA-3095889
Type
Reaction [transition]
Species
Homo sapiens
Compartment
Locations in the PathwayBrowser
General
SVG |   | PPTX  | SBGN
Click the image above or here to open this reaction in the Pathway Browser
The layout of this reaction may differ from that in the pathway view due to the constraints in pathway layout

Methylmalonic aciduria and homocystinuria type C protein (MMACHC aka cblC protein) is suggested to be involved in the binding and intracellular transport of cobalamin (Cbl aka vitamin B12). MMACHC can catalyse the removal of the "R" group (formally called the upper axial ligand) from Cbl (eg dealkylation of AdoCbl and MeCbl or decyanation of CNCbl) which can result in the reduction of Cbl (+3 oxidation state) to cob(II)alamin (B12r, vitamin B12r +2 oxidation state) (Hannibal et al. 2009). Cob(II)alamin is escorted by MMACHC to its destination enzyme partners in the mitochondria and cytosol.

Defects in MMACHC cause methylmalonic aciduria and homocystinuria type cblC (MMAHCC; MIM:277400). MMAHCC is the most common disorder of Cbl metabolism and is characterised by decreased levels of the coenzymes adenosylcobalamin (AdoCbl) and methylcobalamin (MetCbl). Affected individuals may have developmental, haematologic, neurologic, metabolic, ophthalmologic, and dermatologic clinical findings (Lerner-Ellis et al. 2006).

Literature References
PubMed ID Title Journal Year
19447654 Processing of alkylcobalamins in mammalian cells: A role for the MMACHC (cblC) gene product

Hannibal, L, Kim, J, Brasch, NE, Wang, S, Rosenblatt, DS, Banerjee, R, Jacobsen, DW

Mol. Genet. Metab. 2009
16311595 Identification of the gene responsible for methylmalonic aciduria and homocystinuria, cblC type

Lerner-Ellis, JP, Tirone, JC, Pawelek, PD, Doré, C, Atkinson, JL, Watkins, D, Morel, CF, Fujiwara, TM, Moras, E, Hosack, AR, Dunbar, GV, Antonicka, H, Forgetta, V, Dobson, CM, Leclerc, D, Gravel, RA, Shoubridge, EA, Coulton, JW, Lepage, P, Rommens, JM, Morgan, K, Rosenblatt, DS

Nat. Genet. 2006
Participants
Participant Of
Catalyst Activity
Catalyst Activity
Title
oxidoreductase activity of MMACHC [cytosol]
Physical Entity
Activity
Orthologous Events
Authored
Reviewed
Created