FACT (biology)
abundant nuclear complex, which was originally identified in mammalian systems as a factor required for transcription elongation on chromatin templates. The FACT complex has been shown to destablilize the interaction between the H2A/H2B dimer and
FACT (facilitates chromatin transcription, sometimes facilitates chromatin transactions) is a heterodimeric protein complex that affects eukaryotic RNA polymerase II (Pol II) transcription elongation both in vitro and in vivo. It was discovered in 1998 as a factor purified from human cells that was essential for productive, in vitro Pol II transcription on a chromatinized DNA template.
FACT consists of 140 and 80 kilodalton (kDa) subunits. The 140 kDa subunit is encoded by the human gene SUPT16H, (SPT16 in S. cerevisiae) while the 80 kDa subunit is encoded by the human gene SSRP1 (POB3 in S. cerevisiae). Both of these subunits in yeast affect Pol II transcription elongation, and purified human FACT binds specifically to mononucleosomes and the histone H2A/H2B dimer, but not to the H3/H4 tetramer (see: Nucleosome core particle) or Pol II.
Co-immunoprecipitation assays with tagged recombinant proteins showed that the Spt16 subunit interacts with H2A/H2B dimers and mononucleosomes, but not H3/H4 tetramers, whereas the SSRP1 subunit interacts only with H3/H4 tetramers and not mononucleosomes. Deletion of the highly acidic C-terminus of Spt16 (a common feature of known histone chaperones) does not prevent Spt16 from forming a stable complex with SSRP1, but it does eliminate interaction with mononucleosomes and ability to stimulate in vitro transcription on chromatinized templates. The two subunits together, but neither alone, can stimulate formation of nucleosomes from free histones and DNA (histone chaperone activity). These two subunits are highly conserved across all eukaryotes, and in addition to transcription, have been shown to affect DNA repair and replication as well.
In cells, FACT is enriched on parts of the genome involved in actively elongating Pol II, as seen in fluorescent-antibody staining of Drosophila polytene chromosomes and chromatin immunoprecipitation (ChIP) assays on Drosophila Kc cell extracts.
References
Further reading
Reinberg, D., Sims, R. (2006).
“FACT (biology)” enters the record as abundant nuclear complex, which was originally identified in mammalian systems as a factor required for transcription elongation on chromatin templates. The FACT complex has been shown to destablilize the interaction between the H2A/H2B dimer and. Crown Archives preserves that source wording while asking what FACT, biology and abundant can confirm, complicate or overturn.
Why this record matters
“FACT (biology)” is worth following because a concise public description often conceals a longer documentary argument. Here, FACT, biology and abundant provides the most credible route into that argument.
Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated Jul 25, 2024. The linked authority identifier is Q22330037. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1998 and 2006.
Overview language is designed for orientation and should not be treated as a substitute for the evidence cited beneath it. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Use the entry as an orientation point, then follow its citations and revision history. Names, dates and institutional relationships should be checked against the original record.
- Subject orientation
- Search vocabulary
- Locating named sources
The closest primary source, responsible institution and strongest cited specialist reference.
Three-step research path
- Establish the record: confirm the title “FACT (biology)”, its source revision and the description used here.
- Expand the search: follow FACT (biology) primary sources, FACT (biology) archive and FACT research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “FACT (biology)”?
- Which cited source is closest to the event, object or claim?
- Which institution is responsible for the underlying evidence?
Search terms from this dossier
This entry incorporates text from “FACT (biology)” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.