# EXT1

Source: https://onco.cc/targets/ext1/  
OnCo record `ext1` (Target). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

EXT1 (Exostosin-1) is an enzyme. In the public catalogues the evidence so far is association rather than a proven role. Tied to Sarcomas, Breast cancer, Ovarian cancer and 2 more.

## Summary

Glycosyltransferase forming with EXT2 the heterodimeric heparan sulfate polymerase which catalyses the elongation of the heparan sulfate glycan backbone. Glycan backbone extension consists in the alternating transfer of (1->4)-beta-D-GlcA and (1->4)-alpha-D-GlcNAc residues from their respective UDP-sugar donors. Both EXT1 and EXT2 are required for the full activity of the polymerase since EXT1 bears the N-acetylglucosaminyl-proteoglycan 4-beta-glucuronosyltransferase activity within the complex while EXT2 carries the glucuronosyl-N-acetylglucosaminyl-proteoglycan 4-alpha-N-acetylglucosaminyltransferase activity.

Open Targets scores its association with cancer at 0.84 (direct and indirect evidence; datatypes genetic literature 0.81, affected pathway 0.30, literature 0.94, genetic association 0.75, somatic mutation 0.89, animal model 0.72).

## Fields

- Kind: Target
- Last checked: 2026-09-23
- Also known as: exostosin glycosyltransferase 1; Exostosin-1; ttv
- Tags: cancer-genes-wave
- Symbol: EXT1
- Class: enzyme
- Biology: Glycosyltransferase forming with EXT2 the heterodimeric heparan sulfate polymerase which catalyses the elongation of the heparan sulfate glycan backbone. Glycan backbone extension consists in the alternating transfer of (1->4)-beta-D-GlcA and (1->4)-alpha-D-GlcNAc residues from their respective UDP-sugar donors. Both EXT1 and EXT2 are required for the full activity of the polymerase since EXT1 bears the N-acetylglucosaminyl-proteoglycan 4-beta-glucuronosyltransferase activity within the complex while EXT2 carries the glucuronosyl-N-acetylglucosaminyl-proteoglycan 4-alpha-N-acetylglucosaminyltransferase activity. Heparan sulfate proteoglycans are ubiquitous components of the extracellular matrix and play an important role in tissue homeostasis and signalling. Location: Golgi apparatus membrane; Golgi apparatus, cis-Golgi network membrane; Endoplasmic reticulum membrane (UniProt). Locus 8q24.11 (HGNC).
- Where found: Sarcomas: Open Targets association 0.76 with sarcoma (MONDO_0005089); Breast cancer: Open Targets association 0.58 with breast cancer (MONDO_0007254); Ovarian cancer: Open Targets association 0.52 with ovarian cancer (MONDO_0008170); Skin cancer: Open Targets association 0.51 with skin cancer (MONDO_0002898); Chondrosarcoma: Open Targets association 0.75 with chondrosarcoma (MONDO_0008977)

## Notes

- Written by scripts/fetch-cancer-genes.ts from CIViC, Open Targets, IntOGen, HGNC and UniProt; the function text is UniProt's, condensed and in UK spelling. Roles: none stated by the sources. Evidence tier "association-only" is the strongest of those signals.
- Prevalence not recorded: none of the sources gives a positivity rate.

## Sources

- HGNC HGNC:3512: https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:3512
- UniProt Q16394: https://www.uniprot.org/uniprotkb/Q16394/entry
- NCBI Gene 2131: https://www.ncbi.nlm.nih.gov/gene/2131
- Ensembl ENSG00000182197: https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000182197

## Connected records

- collections: [Open Targets Platform](https://onco.cc/collections/open-targets/)
- cancers: [Breast cancer (all types)](https://onco.cc/cancers/breast-cancer/), [Chondrosarcoma](https://onco.cc/cancers/chondrosarcoma/), [Ovarian cancer](https://onco.cc/cancers/ovarian/), [Sarcomas (soft tissue, bone, GIST)](https://onco.cc/cancers/sarcoma/), [Skin cancer (all types)](https://onco.cc/cancers/skin-cancer/)

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JSON: https://onco.cc/api/v1/entities/ext1.json