[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Biochemistry](https://durgical.com/en/biochemistry/) › Transthyretin (prealbumin)

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

# Transthyretin (prealbumin)

Transthyretin carries thyroxine and vitamin A in blood; if its tetramer falls apart, it forms amyloid in the heart and nerves.

Updated 2026-11-01

Loading the 3D model…

## Key facts

- A tetramer of four identical subunits (127 amino acids), made mainly in the liver (and in the choroid plexus for cerebrospinal fluid).
- Carries thyroxine (T4) in two central channels and retinol bound to retinol-binding protein (RBP).
- Rate-limiting step of amyloid: the tetramer splits into monomers, which misfold and form fibrils.
- Variants such as Val30Met (polyneuropathy) or Val122Ile (cardiomyopathy, commoner in people of African ancestry) destabilise the tetramer; normal TTR also forms amyloid in older adults.
- Called prealbumin because it runs ahead of albumin on electrophoresis; half-life ≈ 2 days.

**Also called**
Prealbumin, TTR

**Genes**
TTR

**Structure (PDB)**
[3TCT](https://www.rcsb.org/structure/3TCT)

## Structure

- Structure 3TCT is normal human transthyretin with tafamidis (code 3MI) in the thyroxine channel; the highlighted site is that channel, where the drug bridges two subunits.
- The file holds two chains (A, B); the full tetramer is built by crystal symmetry.

## Regulation

- Falls in inflammation (negative acute-phase reactant) and in protein malnutrition.
- Stabilisers (tafamidis, acoramidis) occupy the T4 site and stop the tetramer from splitting; RNA silencers reduce its synthesis in the liver.

## Inhibitors and toxins

- Tafamidis and acoramidis (tetramer stabilisers)
- TTR RNA silencers (patisiran, vutrisiran, inotersen)

## Clinical notes

- Hereditary TTR amyloidosis: sensorimotor and autonomic polyneuropathy, cardiomyopathy, gut symptoms.
- Wild-type TTR amyloidosis (formerly “senile”): cardiomyopathy in older men, often preceded years earlier by bilateral carpal tunnel syndrome.
- Prealbumin is used as a marker of recent nutritional status, with the caveat that it also falls in inflammation.

## Related conditions

- [Amyloidosis](https://durgical.com/en/conditions/amyloidosis/)
- [Heart failure](https://durgical.com/en/conditions/heart-failure/)
- [Carpal tunnel syndrome](https://durgical.com/en/conditions/carpal-tunnel-syndrome/)

## Related

- [Albumin](https://durgical.com/en/biochemistry/enzymes/albumin/)
- [Plasma proteins and electrophoresis](https://durgical.com/en/biochemistry/topics/plasma-proteins-and-electrophoresis/)
- [Protein structure and folding](https://durgical.com/en/biochemistry/topics/protein-structure-and-folding/)
- [Vitamin A (retinol)](https://durgical.com/en/biochemistry/molecules/vitamin-a/)

## Test yourself

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

## Which molecules does transthyretin carry?

Thyroxine (T4) and, through retinol-binding protein, vitamin A.

## What is the key step for transthyretin to form amyloid?

The tetramer splitting into monomers, which then misfold and aggregate.

## How does tafamidis work?

It binds the thyroxine sites and stabilises the tetramer so it does not split into amyloid-forming monomers.

## Why is it called prealbumin?

Because on protein electrophoresis it runs slightly ahead of albumin, towards the anode.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/biochemistry/enzymes/transthyretin/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [TTR: Transthyretin (human)](https://www.uniprot.org/uniprotkb/P02766/entry) (UniProt, 2026); [TTR gene: MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/ttr/) (MedlinePlus, US National Library of Medicine, 2026); [Transthyretin amyloidosis: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/transthyretin-amyloidosis/) (MedlinePlus, US National Library of Medicine, 2026); [3TCT: Structure of wild-type TTR in complex with tafamidis](https://www.rcsb.org/structure/3TCT) (RCSB Protein Data Bank, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).

[← All of biochemistry](https://durgical.com/en/biochemistry/)

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

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