# MLLT3

Source: https://onco.cc/targets/mllt3/  
OnCo record `mllt3` (Target). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

MLLT3 (MLLT3 super elongation complex subunit) is a protein that switches other genes on and off. The public catalogues list it as a fusion partner, and it is called a cancer driver by mutation analysis of patient cohorts. Tied to Leukaemia, Non-Hodgkin lymphoma and Melanoma.

## Summary

Chromatin reader component of the super elongation complex (SEC), a complex required to increase the catalytic rate of RNA polymerase II transcription by suppressing transient pausing by the polymerase at multiple sites along the DNA. Specifically recognises and binds acylated histone H3, with a preference for histone H3 that is crotonylated. Crotonylation marks active promoters and enhancers and confers resistance to transcriptional repressors.

Open Targets scores its association with cancer at 0.50 (direct and indirect evidence; datatypes literature 0.98, animal model 0.38, genetic association 0.46, somatic mutation 0.65). IntOGen calls it a driver in 1 cohort (0 activating, 0 loss-of-function), covering Melanoma.

## Fields

- Kind: Target
- Last checked: 2026-09-23
- Also known as: MLLT3 super elongation complex subunit; AF-9; AF9; YEATS3
- Tags: cancer-genes-wave
- Symbol: MLLT3
- Class: transcription
- Biology: Chromatin reader component of the super elongation complex (SEC), a complex required to increase the catalytic rate of RNA polymerase II transcription by suppressing transient pausing by the polymerase at multiple sites along the DNA. Specifically recognises and binds acylated histone H3, with a preference for histone H3 that is crotonylated. Crotonylation marks active promoters and enhancers and confers resistance to transcriptional repressors. Recognises and binds histone H3 crotonylated at 'Lys-9' (H3K9cr), and with slightly lower affinity histone H3 crotonylated at 'Lys-18' (H3K18cr). Also recognises and binds histone H3 acetylated and butyrylated at 'Lys-9' (H3K9ac and H3K9bu, respectively), but with lower affinity than crotonylated histone H3. In the SEC complex, MLLT3 is required to recruit the complex to crotonylated histones. Location: Nucleus; Chromosome (UniProt). Locus 9p21.3 (HGNC).
- Where found: Leukaemia: Open Targets association 0.52 with leukaemia (MONDO_0005059); Non-Hodgkin lymphoma: Open Targets association 0.52 with non-Hodgkin lymphoma (MONDO_0018908); Melanoma: IntOGen driver in 1 cohort (MEL)

## 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: UniProt disease notes describe a translocation or gene fusion involving the gene. Evidence tier "cohort-driver" is the strongest of those signals.
- Prevalence not recorded: none of the sources gives a positivity rate.

## Sources

- HGNC HGNC:7136: https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:7136
- UniProt P42568: https://www.uniprot.org/uniprotkb/P42568/entry
- NCBI Gene 4300: https://www.ncbi.nlm.nih.gov/gene/4300
- Ensembl ENSG00000171843: https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000171843

## Connected records

- collections: [IntOGen](https://onco.cc/collections/intogen/), [Open Targets Platform](https://onco.cc/collections/open-targets/)
- cancers: [Leukaemia (all types)](https://onco.cc/cancers/leukaemia/), [Melanoma](https://onco.cc/cancers/melanoma/), [Non-Hodgkin lymphoma (all types)](https://onco.cc/cancers/non-hodgkin-lymphoma/)

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JSON: https://onco.cc/api/v1/entities/mllt3.json