Reaction: Defective ABCD4:LMBRD1 does not transport Cbl from lysosomal lumen to cytosol
- in pathway: Defective ABCD4 causes MAHCJ
ATP-binding cassette sub-family D member 4 (ABCD4) is thought to mediate the lysosomal export of cobalamin (Cbl aka vitamin B12) into the cytosol, making it available for the production of Cbl cofactors. Cbl is an important cofactor for correct haematological and neurological functions. Defects in ABCD4 can cause methylmalonic aciduria and homocystinuria, cblJ type (MAHCJ; MIM:614857), a genetically heterogeneous metabolic disorder of Cbl metabolism characterised by decreased levels of the coenzymes adenosylcobalamin (AdoCbl) and methylcobalamin (MeCbl). Clinically, symptoms include feeding difficulties, poor growth, hypotonia, lethargy, anaemia and delayed development. Mutations causing MAHCJ include Y319C and E583Lfs*9 (Coelho et al. 2012).
Reaction - small molecule participants:
H2O [cytosol]
ATP [cytosol]
Cbl [lysosomal lumen]
Reactome.org reaction link: R-HSA-5683325
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Reaction input - small molecules:
water
ATP(4-)
cob(III)alamin
Reaction output - small molecules:
Reactome.org link: R-HSA-5683325