Preferred Label : Malate-Aspartate Shuttle Pathway;
NCIt related terms : Malate-aspartate shuttle;
Alternative definition : BIOCARTA: Most of the energy derived from the oxidation of glucose is not extracted
directly as ATP, but as reduced NADH that transfers high-energy electrons to the electron
transport chain in the inner mitochondrial membrane. This NADH comes primarily from
the Krebs cycle in the mitochondrial matrix and is therefore directly accessible to
electron transport. NADH generated during glycolysis cannot reach the electron transport
chain directly however and there is no direct mechanism for the transfer of NADH across
the mitochondrial membrane. Instead shuttle mechanisms have evolved to move the energy
of reduced NADH across the membrane in the form of other reduced molecules. One shuttle
is the glycerophosphate shuttle and another is the malate-aspartate shuttle. The malate-aspartate
shuttle occurs in mammalian tissues. First, oxaloacetate on the cytoplasmic side is
reduced by NADH, creating malate and NAD . Malate and the electrons it carries are
transported into the mitochondria across the inner mitochondrial membrane, in exchange
for alpha-ketoglutarate, which is transported out of the mitochondria. Once inside,
the energy in malate is extracted again by reducing NAD to make NADH, regenerating
oxaloacetate. This NADH is then free to transfer its high energy electrons to the
electron transport chain. The oxaloacetate is transaminated with glutamate to make
aspartate and alpha-ketoglutarate. Aspartate is returned to the cytosol by the aspartate-glutamate
transporter, which moves glutamate into the mitochondria as it transports aspartate
out. The overall result is that NADH is transported into the mitochondria, and can
be used to generate 3 ATP per every NADH transported in from the cytosol, a very efficient
process. (This definition may be outdated - see the DesignNote.);
NCIt note : The BIOCARTA Definition (ALT_DEFINITION) for this pathway concept was provided by
BioCarta. This property was not created by, nor is it maintained by the NCI Thesaurus
staff. Additionally, BioCarta is no longer updating its pathway data; thus, the BIOCARTA
Definition might be outdated or inaccurate. Please see the Terms and Conditions for
Use at http://www.biocarta.com/.;
NCI Metathesaurus CUI : CL323266;
Biocarta ID : h_malatePathway;
Origin ID : C39143;
UMLS CUI : C1518158;
Automatic exact mappings (from CISMeF team)
Semantic type(s)
UMLS correspondences (same concept)
has_gene_product_element
pathway_has_gene_element