Isopentenyl pyrophosphate (IPP) !

Isopentenyl pyrophosphate is the five-carbon building block (active isoprene) used to build cholesterol and many other isoprenoids.

Updated 2026-11-01

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Key facts

A five-carbon isoprene unit activated by a pyrophosphate.
The isomerase turns it into dimethylallyl pyrophosphate (DMAPP); the two join head-to-tail.
Six units make squalene (C30), which leads to cholesterol.
It also gives rise to dolichol, ubiquinone (coenzyme Q), haem A and farnesyl and geranylgeranyl groups.

A five-carbon chain with a terminal double bond and a diphosphate at the other end.
The pyrophosphate is a good leaving group: when it leaves, a carbocation forms that joins the next isoprene.

γδ T cells (Vγ9Vδ2) sense accumulated IPP; nitrogen-containing bisphosphonates raise it, which explains the acute-phase fever after the first infusion.
Statins lower IPP and its products; reduced ubiquinone has been proposed to contribute to myopathy.

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

How many carbons does isopentenyl pyrophosphate have, and how many units make squalene?

Five carbons; six units make 30-carbon squalene.

Which molecules besides cholesterol come from IPP?

Dolichol, ubiquinone, haem A and the prenyl groups (farnesyl, geranylgeranyl) on some proteins.

Why does the pyrophosphate make IPP reactive?

It is a good leaving group: its release creates a carbocation that joins another isoprene.

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.

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