OpenScientist function-assignment hypothesis: Mcad (Q9VSA3) medium-chain acyl-CoA dehydrogenase activity (GO:0070991)
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Independent AI-scientist analysis (blinded to our review action, focused on the substrate cavity) strongly supports medium-chain specificity for fly Mcad - 20 of 21 active-site/substrate-binding residues identical to human MCAD, the one substitution (F372 vs L376) conservative, and near-identical AlphaFold active-site geometry - with no support for a different chain-length term.
"The single substitution (F372 in Drosophila vs. L376 in human) is a conservative hydrophobic replacement (both are bulky hydrophobic residues) that maintains the character of the substrate-binding pocket."
Gene Ontology annotation through association of InterPro records with GO terms
Manual transfer of experimentally-verified manual GO annotation data to orthologs by curator judgment of sequence similarity
Annotation inferences using phylogenetic trees
Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt
Combined Automated Annotation using Multiple IEA Methods
Characterization of the Drosophila melanogaster mitochondrial proteome.
Mapping organelle proteins and protein complexes in Drosophila melanogaster.
Phosphorylation of MCAD selectively rescues PINK1 deficiencies in behavior and metabolism.
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Establishes fly Mcad (CG12262) as the medium-chain acyl-CoA dehydrogenase of fatty acid beta-oxidation; loss-of-function models elevate C6/C8/C10:1 acylcarnitines as in human MCAD deficiency, rescued by wild-type Mcad.
"significant elevations in medium-chain acylcarnitines characteristic of human MCAD deficiency: C6, C8, and C10:1 acylcarnitines"
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Mcad is a mitochondrial matrix protein with a secondary cytosolic pool detected by fractionation of fly lysates.
"both endogenous and transgenic MCAD protein localized to the mitochondria as well as the cytosol, consistent with a previous report in mammals"
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Identifies a novel, catalysis-independent role: PINK1-dependent phosphorylation at Ser347 whose phosphomimetic rescues PINK1-null neuromuscular and metabolic phenotypes.
"phosphomimetic MCAD S347 likely rescues PINK1 null's organismal phenotypes independently of MCAD's acyl-CoA dehydrogenase activity"
UniProtKB - Q9VSA3 (ACADM_DROME) Medium-chain specific acyl-CoA dehydrogenase, mitochondrial
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Reviewed Swiss-Prot record for fly Mcad; EC 1.3.8.7, FAD cofactor, mitochondrial matrix / cytosol localization, homotetramer (by similarity), and phosphorylation at Ser-347 by Pink1.
"Name=FAD; Xref=ChEBI:CHEBI:57692"