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[Biochemistry](https://durgical.com/en/biochemistry/) · Molecule

# IMP (inosine monophosphate)

IMP is the first complete purine the cell makes; AMP and GMP come from it.

Updated 2026-11-01

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## Key facts

- End product of de novo purine synthesis and branch point towards AMP and GMP.
- Its base is hypoxanthine; it also forms by salvage (HGPRT) and by AMP deamination.
- IMP → AMP needs GTP and aspartate; IMP → GMP needs NAD⁺, glutamine and ATP.
- It feeds back to inhibit PRPP amidotransferase.

**Also called**
Inosinic acid

**Formula**
C₁₀H₁₃N₄O₈P

**PubChem**
[CID 135398640](https://pubchem.ncbi.nlm.nih.gov/compound/135398640)

## Structure

- Hypoxanthine linked through N9 to a ribose with a phosphate on C5'.
- It is a nucleotide: base + sugar + phosphate.

## Clinical notes

- 6-Mercaptopurine is activated to thio-IMP, which mimics IMP and blocks several pathway enzymes.
- In hard-working muscle, AMP is deaminated to IMP (purine nucleotide cycle).

## Pathways

- [De novo purine synthesis](https://durgical.com/en/biochemistry/pathways/de-novo-purine-synthesis/)
- [Purine degradation and salvage](https://durgical.com/en/biochemistry/pathways/purine-degradation-and-salvage/)

## Related conditions

- [Lesch-Nyhan syndrome](https://durgical.com/en/conditions/lesch-nyhan-syndrome/)

## Related

- [IMP dehydrogenase (IMPDH)](https://durgical.com/en/biochemistry/enzymes/imp-dehydrogenase/)
- [Hypoxanthine-guanine phosphoribosyltransferase (HGPRT)](https://durgical.com/en/biochemistry/enzymes/hypoxanthine-guanine-phosphoribosyltransferase/)
- [Hypoxanthine](https://durgical.com/en/biochemistry/molecules/hypoxanthine/)
- [Glutamine-PRPP amidotransferase](https://durgical.com/en/biochemistry/enzymes/glutamine-prpp-amidotransferase/)
- [ATP (adenosine triphosphate)](https://durgical.com/en/biochemistry/molecules/atp/)

## Test yourself

Think of the answer, then tap the question to see it.

## What is the base of IMP?

Hypoxanthine.

## Which energy source does each branch from IMP use?

The AMP branch uses GTP and the GMP branch uses ATP, so each purine promotes the synthesis of the other.

## Why is IMP called a branch point?

Because it is the common product of de novo synthesis and from it the cell decides to make AMP or GMP.

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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: [Inosinic Acid (CID 135398640)](https://pubchem.ncbi.nlm.nih.gov/compound/135398640) (PubChem, NCBI, 2026) · Public domain; [Purine ribonucleoside monophosphate biosynthesis](https://reactome.org/PathwayBrowser/#/R-HSA-73817) (Reactome, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/biochemistry/molecules/imp/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/biochemistry/molecules/imp/