HLF (hepatic leukemia factor) domain architecture
also called HLF · hepatic leukemia factor
HLF is the 3' partner of TCF3::HLF, a rare and historically near-uniformly fatal B-ALL. This entry lists where each of its functional parts sits along the protein, measured as residue numbers, so the fusion diagrams can draw which parts survive the break and which are thrown away.
The same thing, for a scientist
Reference domain architecture for HLF (UniProt Q16534, 295 aa). A PAR-family bZIP transcription factor. The bZIP domain at 225-288 splits into a basic DNA-contacting motif (227-247) and a leucine zipper (248-255). Created so the 3D fusion viewer can resolve fusion-tcf3-hlf, which previously had no coordinates for this partner and silently dropped the lane. Domain fate in the fusion is asserted by the fusion entry, not here.
This is a prediction, not a measurement. No one has seen this protein in this shape. The colours say how much the software trusts itself, and that is worth reading before anything else — the orange stretches are places the model is effectively saying this part has no fixed shape.
I have never read one of these pictures before
A protein is one long chain of amino acids that folds up. The ribbon traces that chain from one end to the other; it is not a wire, it is a simplification of where the backbone runs. Drag to rotate, scroll to zoom.
Domains are the stretches of chain that do a particular job, and they are what the coloured blocks above the picture mark out. Click one and the view flies to it. In this project the important question about any domain is usually whether the fusion still has it — the labels say lost where it does not.
Anything in yellow sticks is a bound small molecule, which is usually the drug.
Why this entry exists
The join checker reported fusion-tcf3-hlf: no protein entry for HLF. Without coordinates the comparative 3D viewer cannot draw the lane at all, and it was omitting it without warning rather than flagging it. This is a reference-coordinate entry: it asserts the architecture and nothing about the fusion.
Folded domains versus functional regions. UniProt mixes two very different annotation kinds. Domain, Zinc finger and DNA binding are fold calls with real boundaries. Region is a functional assertion that often spans disorder and can overlap other regions or run for hundreds of residues. Both are recorded with boundary_precision marking which is which, because drawing a soft functional region as a crisp box is exactly the kind of false precision this graph exists to avoid.
Architecture
| Part | Residues | Kind | Precision |
|---|---|---|---|
| bZIP | 225-288 | Domain | firm |
| Required for transcriptional activation | 60-102 | Region | soft |
| Basic motif | 227-247 | Region | soft |
| Leucine-zipper | 248-255 | Region | soft |
No PDB entry references this protein. Any structural claim about it rests on prediction alone.
| uniprot | Q16534 |
|---|---|
| gene symbol | HLF |
| length AA | 295 |
| protein name | Transcription factor HLF |
| alphafold ID | AF-Q16534-F1 |
| n PDB total | 0 |
| uniprot verified | true |
| accession resolution | exact gene-name search, reviewed human only, gene symbol confirmed in the response |
| created for | fusion-tcf3-hlf |
domains — the numbers behind the chart
[
{
"name": "bZIP",
"start": 225,
"end": 288,
"feature_type": "Domain",
"note": "UniProt folded-domain call.",
"boundary_precision": "firm"
},
{
"name": "Required for transcriptional activation",
"start": 60,
"end": 102,
"feature_type": "Region",
"note": "UniProt functional region, not a fold boundary. Soft edges; render as low confidence.",
"boundary_precision": "soft"
},
{
"name": "Basic motif",
"start": 227,
"end": 247,
"feature_type": "Region",
"note": "UniProt functional region, not a fold boundary. Soft edges; render as low confidence.",
"boundary_precision": "soft"
},
{
"name": "Leucine-zipper",
"start": 248,
"end": 255,
"feature_type": "Region",
"note": "UniProt functional region, not a fold boundary. Soft edges; render as low confidence.",
"boundary_precision": "soft"
}
]PDB IDS
[]
- Nothing here licenses targeting any part of HLF. These are coordinates, not a druggability claim; a domain with crisp boundaries is not thereby a ligandable pocket.
- Drawing UniProt `Region` features as boxes in the viewer risks implying structural knowledge that does not exist. They are marked soft and should be rendered differently from fold calls.
- Where does the fusion-tcf3-hlf breakpoint fall relative to these boundaries, and is the junction codon actually mapped or only inferred from cDNA?
- Which of these parts are retained in the fusion, and is retention ever being confused with requirement for transformation?
- Do InterPro and the deposited crystal constructs agree with these UniProt boundaries? Where they do not, the disagreement should be recorded rather than silently resolved in UniProt's favour.
- E1strong confidence 4 of 5: Replicated in peer-reviewed work by more than one group.dataset
Human HLF (Transcription factor HLF) is 295 residues (UniProt Q16534) with the domain and region boundaries tabulated in this entry, and is referenced by 0 PDB entries.
UniProtKB Q16534 (HLF_HUMAN): sequence length, domain, zinc-finger, DNA-binding, repeat, motif and region features, and PDB cross-references · UniProt Consortium · UniProtKB 2026What this evidence cannot show
Accession resolved by exact gene-name search restricted to reviewed human entries and confirmed against the gene symbol returned, because a previous lookup in this project silently resolved to the wrong gene. Coordinates are for the canonical isoform only; several of these proteins have isoforms that shift numbering. UniProt `Region` features are curator functional calls, not folds.
Evidence that argues against this (1)
- Domain boundaries are not a settled fact and differ between sources. InterPro, Pfam, SMART and individual crystal-structure constructs routinely disagree with UniProt by tens of residues, and published figures often use construct boundaries rather than database ones. Any downstream claim that a breakpoint falls just inside or just outside a domain is therefore only as firm as the boundary definition it assumes, which for every `Region` feature here is soft. InterPro Consortium 2026
- ← related toTCF3::HLF (E2A-HLF), t(17;19)(q22;p13)
Counter-evidence: Inukai 1998 (PMID 9742120) shows the unsolved HLF bZIP is dispensable for the fusion's anti-apoptotic output, so the missing structure is not the limiting gap
- analogous to →GLIS2 (GLI-similar 2) domain architecture
both contribute a sequence-specific DNA-binding module to a fusion rather than an enzyme
reference domain coordinates for the HLF side of this fusion