Biochemistry · Molecule
Malonyl-CoA !
Malonyl-CoA is both the building block of fat synthesis and the signal that stops fat being burned at the same time.
Updated 2026-11-01
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Key facts
- Made by acetyl-CoA carboxylase from acetyl-CoA, bicarbonate and ATP (biotin).
- Donates 2 carbons to each fatty acid synthase turn; the third carbon leaves as CO₂.
- Inhibits CPT-I: it closes the gate for fatty acids into the mitochondrion.
- Rises with insulin (feeding) and falls with glucagon, adrenaline and AMPK (fasting, exercise).
- Also called
- Malonyl coenzyme A
- Formula
- C₂₄H₃₈N₇O₁₉P₃S
- PubChem
- CID 644066
Structure
- A malonyl group (3 C, with a free carboxyl) linked by a thioester to coenzyme A.
Clinical notes
- Its decarboxylase (MLYCD) is missing in malonic aciduria, with hypoglycaemia and cardiomyopathy.
- In the hypothalamus malonyl-CoA takes part in the satiety signal.
Pathways
Related conditions
Related
- Acetyl-CoA carboxylase (ACC)
- Fatty acid synthase (FAS)
- Carnitine palmitoyltransferase I (CPT-I)
- Acetyl-CoA
- Carnitine shuttle
Test yourself
Think of the answer, then tap the question to see it.
Which enzyme makes malonyl-CoA?
Acetyl-CoA carboxylase, with biotin and ATP.
Which β-oxidation enzyme does malonyl-CoA inhibit?
Carnitine palmitoyltransferase I (CPT-I).
What happens to the carboxyl that ACC adds to malonyl-CoA?
It leaves as CO₂ at condensation; that release makes the step irreversible.
Molecules are shown in their neutral form, as the databases deposit them; in the cell the acids and phosphates are ionised.
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Malonyl CoA (CID 644066) (PubChem, NCBI, 2026) · Public domain; Fatty acyl-CoA biosynthesis (Reactome, 2026); Carnitine shuttle (Reactome, 2026).
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