BACH2

Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0006357 regulation of transcription by RNA polymerase II	IBA GO_REF:0000033	ACCEPT	Summary: IBA annotation placing BACH2 as a regulator of RNA Pol II transcription, inferred from phylogenetic analysis of the CNC-bZIP family. BACH2 is a well-established transcriptional regulator that binds MARE elements as a heterodimer with small MAF proteins and modulates Pol II-dependent gene expression in lymphocytes (PMID:28530713, PMID:27052415). Reason: This is a core function of BACH2. As a bZIP transcription factor, it directly regulates Pol II-dependent transcription. The IBA annotation is well supported by the phylogenetic relationship of BACH2 to other CNC-bZIP family members (NRF2, BACH1, NFE2L1) that all regulate Pol II transcription. The annotation is at the right level of generality for an IBA inference since BACH2 can act as both repressor and (in some contexts) activator. Supporting Evidence: PMID:17018862 we showed that Bach2 transcriptionally represses heme oxygenase-1, an antiapoptotic factor up-regulated in CML PMID:28530713 BACH2 is a typical example of an SE-regulated gene associated with autoimmune disease. It is a highly conserved member of the basic and leucine zipper domain (bZIP) superfamily of TFs and a critical regulator of both T and B lymphocyte differentiation and maturation
GO:0000978 RNA polymerase II cis-regulatory region sequence-specific DNA binding	IBA GO_REF:0000033	ACCEPT	Summary: IBA annotation for sequence-specific DNA binding at Pol II cis-regulatory regions. BACH2 contains a bZIP DNA-binding domain (residues 646-709) and binds MARE motifs (TRE/CRE-like sequences with flanking TGC) as a heterodimer with small MAF proteins. This has been demonstrated by SELEX (PMID:28473536) and is consistent with its role as a sequence-specific DNA-binding transcription factor. Reason: BACH2 has a characterized bZIP DNA-binding domain and binds specific DNA sequences (MARE elements) at regulatory regions. The IBA annotation is phylogenetically consistent and directly supported by experimental evidence showing sequence-specific DNA binding via SELEX analysis (PMID:28473536). Supporting Evidence: PMID:28473536 By analysis of 542 human TFs with methylation-sensitive SELEX (systematic evolution of ligands by exponential enrichment), we found that there are also many TFs that prefer CpG-methylated sequences
GO:0000981 DNA-binding transcription factor activity, RNA polymerase II-specific	IBA GO_REF:0000033	ACCEPT	Summary: IBA annotation for DNA-binding transcription factor activity (Pol II-specific). BACH2 is a bona fide sequence-specific DNA-binding transcription factor that modulates Pol II transcription. It primarily acts as a transcriptional repressor, though it can also activate transcription in some contexts (UniProt, by similarity). Given BACH2's predominant repressor function, a more specific child term (GO:0001227, DNA-binding transcription repressor activity, RNA polymerase II-specific) would be more informative, but the parent term is not wrong. Reason: The IBA annotation is correct and at a reasonable level of specificity since the phylogenetic inference groups BACH2 with family members that can act as both activators and repressors. BACH2 is primarily a repressor but has been reported to also activate in some contexts, so the parent term GO:0000981 is defensible. Supporting Evidence: PMID:27052415 The transcription factors Bach1 and Bach2, which belong to a basic region-leucine zipper (bZip) family, repress target gene expression by forming heterodimers with small Maf proteins
GO:0003677 DNA binding	IEA GO_REF:0000120	ACCEPT	Summary: IEA annotation for generic DNA binding based on combined automated methods including InterPro domain matches (bZIP, bZIP_Maf) and orthology to mouse BACH2 (P97303). BACH2 does bind DNA through its bZIP domain, but this term is very general and is subsumed by the more specific annotations already present. Reason: While overly general, IEA annotations to broad parent terms are acceptable when more specific annotations exist. The more specific GO:0000978 (IBA) and GO:1990837 (IDA) already capture the DNA binding activity of BACH2 more precisely. This IEA annotation is not wrong and will be naturally superseded. Supporting Evidence: PMID:28473536 By analysis of 542 human TFs with methylation-sensitive SELEX (systematic evolution of ligands by exponential enrichment), we found that there are also many TFs that prefer CpG-methylated sequences
GO:0003700 DNA-binding transcription factor activity	IEA GO_REF:0000120	ACCEPT	Summary: IEA annotation for generic DNA-binding transcription factor activity based on InterPro domain matches and orthology. This is the parent of GO:0000981 which is already annotated via IBA. The annotation is correct but less specific. Reason: Correct but general. The more specific GO:0000981 (IBA) already captures the Pol II-specific transcription factor activity. This broader IEA term is acceptable as a computationally derived parent annotation.
GO:0005634 nucleus	IEA GO_REF:0000120	ACCEPT	Summary: IEA annotation for nuclear localization based on combined automated methods including orthology to mouse BACH2 and UniProt subcellular location data. BACH2 localizes to the nucleus where it functions as a transcriptional repressor. Nuclear localization is experimentally confirmed (PMID:17018862, PMID:28530713) and noted in UniProt. Reason: Correct. BACH2 functions in the nucleus as a transcription factor. UniProt confirms nuclear localization supported by experimental evidence from PMID:17018862 and PMID:28530713. BACH2 undergoes regulated nucleocytoplasmic shuttling, but the nucleus is a primary functional location. Supporting Evidence: PMID:17018862 Bach2 is phosphorylated on S521 via the phosphatidylinositol-3/S6 kinase pathway, and substitution of this site to alanine leads to nuclear accumulation of the protein, indicating that this phosphorylation is important for its subcellular localization PMID:28530713 BACH2 dimers translocate to the nucleus where they interact with target DNA loci at palindromic Maf recognition elements (MARE), either alone or in collaboration with other members of the bZIP family, such as the small Maf proteins (MafF, MafG and MafK)
GO:0005737 cytoplasm	IEA GO_REF:0000044	ACCEPT	Summary: IEA annotation for cytoplasmic localization based on UniProt subcellular location vocabulary mapping. UniProt lists cytoplasm as a subcellular location for BACH2, supported by experimental evidence showing that PI3K-AKT-dependent phosphorylation at Ser-521 promotes cytoplasmic accumulation (PMID:17018862). BACH2 also forms cytoplasmic aggregates when mutated (E788K variant in IMD60). Reason: Correct. BACH2 undergoes regulated nucleocytoplasmic shuttling. Phosphorylation at Ser-521 downstream of the PI3K pathway promotes cytoplasmic localization (PMID:17018862). The cytoplasm is a bona fide subcellular location for BACH2, particularly in its inactive/phosphorylated state. Supporting Evidence: PMID:17018862 Bach2 is phosphorylated on S521 via the phosphatidylinositol-3/S6 kinase pathway, and substitution of this site to alanine leads to nuclear accumulation of the protein, indicating that this phosphorylation is important for its subcellular localization PMID:28530713 we found that wild-type BACH2 protein was evenly distributed in both cytoplasm and nucleus, whereas the E788K mutant protein was aggregated in the cytoplasm with relatively little in the nucleus
GO:0006355 regulation of DNA-templated transcription	IEA GO_REF:0000002	ACCEPT	Summary: IEA annotation for regulation of DNA-templated transcription based on InterPro domain associations (bZIP, bZIP_Maf, TF_DNA-bd domains). This is a parent term of GO:0006357 (regulation of transcription by RNA polymerase II) which is already annotated via IBA. Reason: Correct but more general than GO:0006357 already captured by IBA. As an IEA derived from domain associations, this broad annotation is acceptable and will be naturally superseded by the more specific annotations.
GO:0005515 protein binding	IPI PMID:23661758 Networks of bZIP protein-protein interactions diversified ov...	MODIFY	Summary: IPI annotation for protein binding based on the Reinke et al. 2013 study that systematically measured bZIP dimerization networks across species. The with/from fields indicate interactions with MAFG (O15525), BATF3 (Q9NR55), and MAFF (Q9ULX9). These are biologically meaningful interactions: small MAF proteins are the canonical dimerization partners of BACH2 for DNA binding, and BATF3 is a bZIP family member. However, 'protein binding' is uninformative. Reason: The interactions with MAFG, MAFF, and BATF3 are biologically relevant dimerization events for a bZIP transcription factor. However, GO:0005515 (protein binding) is uninformative per GO curation guidelines. The actual function is DNA-binding transcription factor activity enabled by dimerization with small MAF proteins. The protein-protein interactions are integral to the transcription factor activity and are better captured by the ComplexPortal entries (CPX-2484 for BACH2-MAFF, CPX-2485 for BACH2-MAFG). Proposed replacements: protein homodimerization activity protein heterodimerization activity Supporting Evidence: PMID:23661758 We studied the basic region-leucine zipper (bZIP) transcription factors and quantified bZIP dimerization networks for five metazoan and two single-cell species, measuring interactions in vitro for 2891 protein pairs
GO:0005515 protein binding	IPI PMID:28514442 Architecture of the human interactome defines protein commun...	MODIFY	Summary: IPI annotation for protein binding based on BioPlex 2.0 high-throughput AP-MS study (Huttlin et al. 2017). The with/from fields include TULP3 (O75386), FOSL2 (P15408), BATF3 (Q9NR55), and MAFF (Q9ULX9). The interactions with FOSL2 (an AP-1 factor) and small MAFs are biologically meaningful for a bZIP TF, but TULP3 interaction is likely from high-throughput noise. Reason: High-throughput AP-MS data. Some interactors (FOSL2, BATF3, MAFF) are biologically plausible bZIP dimerization partners. Others (TULP3) may be spurious. GO:0005515 is uninformative per curation guidelines. Proposed replacements: protein heterodimerization activity Supporting Evidence: PMID:28514442 Architecture of the human interactome defines protein communities and disease networks
GO:0005515 protein binding	IPI PMID:32296183 A reference map of the human binary protein interactome	MODIFY	Summary: IPI annotation for protein binding based on the HuRI reference binary interactome study (Luck et al. 2020). This study identified numerous interaction partners including MAFG (O15525), MAFK (O60675), FOSL2 (P15408), BATF3 (Q9NR55), and many other proteins. The MAF/BATF3 interactions are biologically meaningful as canonical bZIP dimerization partners. Many others (CTSZ, CENPP, CFAP58, etc.) are likely high-throughput artifacts. Reason: Large-scale binary interactome study. GO:0005515 is uninformative. The meaningful interactions (with MAF proteins and bZIP family members) reflect heterodimerization activity integral to transcription factor function. Proposed replacements: protein heterodimerization activity Supporting Evidence: PMID:32296183 A reference map of the human binary protein interactome
GO:0005515 protein binding	IPI PMID:33961781 Dual proteome-scale networks reveal cell-specific remodeling...	MODIFY	Summary: IPI annotation for protein binding based on BioPlex 3.0 (Huttlin et al. 2021). Interactors include MAFG (O15525), MAFK (O60675), MAFF (Q9ULX9), FOSL2 (P15408), BATF3 (Q9NR55), ZBTB24, and ZBTB34. The MAF interactions are canonical and biologically validated. Reason: Proteome-scale interactome study. GO:0005515 is uninformative per curation guidelines. The biologically meaningful interactions are bZIP dimerization with small MAFs and other bZIP family members. Proposed replacements: protein heterodimerization activity Supporting Evidence: PMID:33961781 Dual proteome-scale networks reveal cell-specific remodeling of the human interactome
GO:0005515 protein binding	IPI PMID:40205054 Multimodal cell maps as a foundation for structural and func...	MODIFY	Summary: IPI annotation for protein binding from multimodal cell maps study (Schaffer et al. 2025). The with/from field indicates interaction with MAFK (O60675), a canonical small MAF dimerization partner of BACH2. Reason: GO:0005515 is uninformative. The MAFK interaction is a canonical bZIP heterodimerization that is integral to BACH2's transcription factor function. Proposed replacements: protein heterodimerization activity Supporting Evidence: PMID:40205054 Multimodal cell maps as a foundation for structural and functional genomics
GO:0000122 negative regulation of transcription by RNA polymerase II	IEA GO_REF:0000107	ACCEPT	Summary: IEA annotation transferred from mouse ortholog (P97303) via Ensembl Compara. BACH2 is well established as a transcriptional repressor. It represses PRDM1 (Blimp-1) to maintain germinal center programs in B cells, and represses effector gene programs (Gata3, Irf4, Prdm1, Gzmb) in T cells. The mouse ortholog has extensive experimental evidence for transcriptional repression. Reason: Correct and central to BACH2 biology. BACH2 is predominantly a transcriptional repressor. PMID:17018862 shows repression of HMOX1, and PMID:28530713 shows BACH2 represses PRDM1 to control B cell differentiation. This IEA from Ensembl Compara is well supported by the biology. Supporting Evidence: PMID:17018862 we showed that Bach2 transcriptionally represses heme oxygenase-1, an antiapoptotic factor up-regulated in CML PMID:28530713 In B cells, BACH2 controls the balance between Pax5 and Blimp1 by repressing the latter
GO:0000978 RNA polymerase II cis-regulatory region sequence-specific DNA binding	IEA GO_REF:0000107	ACCEPT	Summary: IEA annotation transferred from mouse ortholog via Ensembl Compara. Duplicates the IBA annotation for the same term. BACH2 does bind DNA in a sequence-specific manner at Pol II-regulated genes. Reason: Correct and consistent with the IBA annotation for the same term. Duplication of evidence from different sources (IBA and IEA) is normal and acceptable.
GO:0001227 DNA-binding transcription repressor activity, RNA polymerase II-specific	IEA GO_REF:0000107	ACCEPT	Summary: IEA annotation for transcription repressor activity transferred from mouse ortholog via Ensembl Compara. This is the most specific and accurate molecular function term for BACH2, which primarily functions as a DNA-binding transcriptional repressor at MARE elements in Pol II-transcribed genes. Reason: This is the most accurate MF term for BACH2's primary molecular function. BACH2 predominantly represses transcription by binding MARE elements as a heterodimer with small MAF proteins. It represses PRDM1/Blimp-1 in B cells and effector gene programs in T cells. Per GO TF annotation guidelines, a child of GO:0000981 specifying repressor activity is the ideal annotation for a predominantly repressive DNA-binding transcription factor. Supporting Evidence: PMID:17018862 we showed that Bach2 transcriptionally represses heme oxygenase-1, an antiapoptotic factor up-regulated in CML PMID:28530713 BACH2 acts as a repressive "guardian" TF that regulates the balance between a network of other TFs critical to T and B cell specification and maturation
GO:0005654 nucleoplasm	IDA GO_REF:0000052	ACCEPT	Summary: IDA annotation for nucleoplasm localization based on HPA immunofluorescence data curation. BACH2 functions in the nucleoplasm as a transcription factor. When in the nucleus, it would be expected to be in the nucleoplasm where it accesses chromatin and regulatory DNA elements. Reason: Correct. BACH2 is a transcription factor that functions in the nucleoplasm. IDA from HPA immunofluorescence is appropriate evidence for subcellular localization.
GO:0005829 cytosol	IDA GO_REF:0000052	ACCEPT	Summary: IDA annotation for cytosol localization based on HPA immunofluorescence data. BACH2 is known to undergo regulated nucleocytoplasmic shuttling, with PI3K-AKT-dependent phosphorylation at Ser-521 promoting cytoplasmic accumulation (PMID:17018862). The cytosol is a bona fide localization for the inactive/phosphorylated form. Reason: Correct. BACH2 accumulates in the cytoplasm/cytosol when phosphorylated by the PI3K-AKT pathway. This is more specific than GO:0005737 (cytoplasm) already annotated via IEA. HPA immunofluorescence data supports this. Supporting Evidence: PMID:17018862 Bach2 is phosphorylated on S521 via the phosphatidylinositol-3/S6 kinase pathway, and substitution of this site to alanine leads to nuclear accumulation of the protein, indicating that this phosphorylation is important for its subcellular localization
GO:0000122 negative regulation of transcription by RNA polymerase II	NAS PMID:27052415 The Bach Family of Transcription Factors: A Comprehensive Re...	ACCEPT	Summary: NAS annotation from ComplexPortal for negative regulation of Pol II transcription, citing PMID:27052415 (Zhou et al. 2016). This review describes how BACH2 represses target gene expression by forming heterodimers with small Maf proteins. BACH2's primary role as a transcriptional repressor is well documented across multiple studies. Reason: Correct and well supported. PMID:27052415 is a comprehensive review of the Bach family of transcription factors that clearly describes BACH2 as repressing target gene expression. The same term is also annotated via IEA from Ensembl Compara. Both annotations are correct for this core function of BACH2. Supporting Evidence: PMID:27052415 The transcription factors Bach1 and Bach2, which belong to a basic region-leucine zipper (bZip) family, repress target gene expression by forming heterodimers with small Maf proteins
GO:0005634 nucleus	NAS PMID:23661758 Networks of bZIP protein-protein interactions diversified ov...	ACCEPT	Summary: NAS annotation from ComplexPortal for nuclear localization, citing the Reinke et al. 2013 bZIP network study. This study characterized bZIP protein-protein interactions in vitro and does not directly demonstrate nuclear localization. However, nuclear localization is well established for BACH2 from other studies. Reason: Nuclear localization of BACH2 is well supported by multiple lines of evidence (PMID:17018862, PMID:28530713, UniProt subcellular location). The NAS evidence code from ComplexPortal is acceptable since BACH2 functions as a nuclear transcription factor in complex with MAF proteins. Supporting Evidence: PMID:28530713 BACH2 dimers translocate to the nucleus where they interact with target DNA loci at palindromic Maf recognition elements (MARE), either alone or in collaboration with other members of the bZIP family, such as the small Maf proteins (MafF, MafG and MafK)
GO:0005634 nucleus	NAS PMID:27052415 The Bach Family of Transcription Factors: A Comprehensive Re...	ACCEPT	Summary: NAS annotation from ComplexPortal for nuclear localization, citing PMID:27052415 (Zhou et al. 2016). This review confirms BACH2 is a nuclear transcription factor that represses gene expression. Reason: Correct. Nuclear localization is well established for BACH2 as a transcription factor. PMID:27052415 describes BACH2 as a transcription factor that represses target gene expression, which requires nuclear localization. This is consistent with the other nuclear localization annotations from IEA, NAS, and IDA evidence. Supporting Evidence: PMID:27052415 The transcription factors Bach1 and Bach2, which belong to a basic region-leucine zipper (bZip) family, repress target gene expression by forming heterodimers with small Maf proteins
GO:0006357 regulation of transcription by RNA polymerase II	NAS PMID:23661758 Networks of bZIP protein-protein interactions diversified ov...	ACCEPT	Summary: NAS annotation from ComplexPortal for regulation of Pol II transcription, citing the Reinke et al. 2013 bZIP dimerization study. The study demonstrated BACH2 forms heterodimers with small MAF proteins and other bZIP factors, consistent with regulation of Pol II transcription. This is a duplicate of the IBA annotation for the same term. Reason: Correct. BACH2 regulates Pol II transcription as a bZIP transcription factor. The NAS evidence from ComplexPortal is based on the bZIP dimerization data. Same term already captured by IBA with stronger phylogenetic evidence. Supporting Evidence: PMID:23661758 We studied the basic region-leucine zipper (bZIP) transcription factors and quantified bZIP dimerization networks for five metazoan and two single-cell species, measuring interactions in vitro for 2891 protein pairs
GO:1990837 sequence-specific double-stranded DNA binding	IDA PMID:28473536 Impact of cytosine methylation on DNA binding specificities ...	ACCEPT	Summary: IDA annotation for sequence-specific double-stranded DNA binding based on Yin et al. 2017, a systematic SELEX study of 542 human TFs. BACH2 was among the TFs tested, and its binding specificities to double-stranded DNA sequences were characterized. This directly demonstrates BACH2 binds specific dsDNA sequences. Reason: Strong experimental evidence (IDA from SELEX) directly demonstrating that BACH2 binds specific dsDNA sequences. This is consistent with BACH2's bZIP domain and its function as a sequence-specific DNA-binding transcription factor that recognizes MARE motifs. Supporting Evidence: PMID:28473536 By analysis of 542 human TFs with methylation-sensitive SELEX (systematic evolution of ligands by exponential enrichment), we found that there are also many TFs that prefer CpG-methylated sequences
GO:0090721 primary adaptive immune response involving T cells and B cells	IMP PMID:28530713 BACH2 immunodeficiency illustrates an association between su...	KEEP AS NON CORE	Summary: IMP annotation for involvement in primary adaptive immune response based on Afzali et al. 2017, which characterized human BACH2 haploinsufficiency (BRIDA/IMD60). Patients with heterozygous BACH2 variants showed impaired lymphocyte maturation, decreased immunoglobulin production, and autoimmunity, demonstrating BACH2 is essential for proper adaptive immune responses. Reason: While BACH2 is clearly required for proper adaptive immune function (as demonstrated by the BRIDA phenotype), this is a very broad biological process term that describes the downstream consequence of BACH2's transcriptional repressor activity rather than its core molecular function. The primary role of BACH2 is as a DNA-binding transcriptional repressor; its involvement in adaptive immunity is a downstream effect of that core function in lymphocytes. Marking as non-core since the annotation is correct but represents a broad organismal phenotype rather than a core molecular-level function. Supporting Evidence: PMID:28530713 Here we describe a syndrome of BACH2-related immunodeficiency and autoimmunity (BRIDA) that results from BACH2 haploinsufficiency. Affected subjects had lymphocyte-maturation defects that caused immunoglobulin deficiency
GO:0000785 chromatin	ISA GO_REF:0000113	ACCEPT	Summary: ISA annotation for chromatin localization based on TFClass database annotation of BACH2 as a sequence-specific DNA-binding transcription factor (class 1.1.1, basic leucine zipper factors / Jun-related). TFClass classification places BACH2 as a DNA-binding TF expected to localize to chromatin when bound to DNA. Reason: Correct. As a DNA-binding transcription factor, BACH2 localizes to chromatin where it binds MARE elements. ChIP-seq studies in lymphocytes have mapped BACH2 binding across the genome. The ISA inference from TFClass classification is sound.
GO:0000981 DNA-binding transcription factor activity, RNA polymerase II-specific	ISA GO_REF:0000113	ACCEPT	Summary: ISA annotation for DNA-binding transcription factor activity based on TFClass database classification (class 1.1.1). This duplicates the IBA annotation for the same term. TFClass independently confirms BACH2 as a bona fide DNA-binding transcription factor. Reason: Correct and consistent with the IBA annotation. TFClass independently classifies BACH2 as a DNA-binding transcription factor (basic leucine zipper factor class). Duplicate annotations from independent evidence sources are acceptable.

Core Functions

BACH2 functions primarily as a sequence-specific DNA-binding transcriptional repressor. It heterodimerizes with small MAF proteins (MAFK, MAFG, MAFF) via its bZIP domain to bind MARE elements and repress target gene transcription. In B cells, it represses PRDM1/Blimp-1 to maintain germinal center identity. In T cells, it represses effector gene programs (Prdm1, Gata3, Irf4, Gzmb) to stabilize Treg identity and promote memory/stem-like CD8+ T cell states. It also represses HMOX1 in the context of oxidative stress responses.

Molecular Function:

DNA-binding transcription repressor activity, RNA polymerase II-specific

Directly Involved In:

negative regulation of transcription by RNA polymerase II B cell differentiation primary adaptive immune response involving T cells and B cells

Cellular Locations:

nucleoplasm

Supporting Evidence:

PMID:17018862
we showed that Bach2 transcriptionally represses heme oxygenase-1, an antiapoptotic factor up-regulated in CML
PMID:28530713
BACH2 acts as a repressive "guardian" TF that regulates the balance between a network of other TFs critical to T and B cell specification and maturation

BACH2 heterodimerizes with small MAF proteins (MAFF, MAFG, MAFK) and other bZIP family members (BATF3, FOSL2) via its bZIP leucine zipper domain. Heterodimerization with small MAFs is essential for DNA binding and transcriptional repression at MARE elements. BACH2 also homodimerizes via its BTB/POZ domain (residues 37-103), forming a disulfide-linked dimer through Cys-20.

Molecular Function:

protein heterodimerization activity

Cellular Locations:

nucleoplasm

Supporting Evidence:

PMID:23661758
We studied the basic region-leucine zipper (bZIP) transcription factors and quantified bZIP dimerization networks for five metazoan and two single-cell species, measuring interactions in vitro for 2891 protein pairs
PMID:22194330
the crystal structure of the human Bach2 POZ domain is reported at 2.1 Å resolution

References

GO_REF:0000002

Gene Ontology annotation through association of InterPro records with GO terms

GO_REF:0000033

Annotation inferences using phylogenetic trees

GO_REF:0000044

Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt

GO_REF:0000052

Gene Ontology annotation based on curation of immunofluorescence data

GO_REF:0000107

Automatic transfer of experimentally verified manual GO annotation data to orthologs using Ensembl Compara

GO_REF:0000113

Gene Ontology annotation of human sequence-specific DNA binding transcription factors (DbTFs) based on the TFClass database

GO_REF:0000120

Combined Automated Annotation using Multiple IEA Methods

PMID:10949928

Cloning and expression of human B cell-specific transcription factor BACH2 mapped to chromosome 6q15

Original cloning of human BACH2 as a B cell-specific transcription factor belonging to the CNC-bZIP family.

"The transcription factor Bach2, a member of the BTB-basic region leucine zipper (bZip) factor family, binds to a 12-O-tetradecanoylphorbol-13-acetate (TPA)-responsive element and the related Maf-recognition element (MARE) by forming homodimers or heterodimers with Maf-related transcription factors."

PMID:17018862

Bcr-Abl signaling through the PI-3/S6 kinase pathway inhibits nuclear translocation of the transcription factor Bach2, which represses the antiapoptotic factor heme oxygenase-1

Demonstrated that BACH2 represses HMOX1 transcription. BCR-ABL/PI3K/S6K signaling phosphorylates BACH2 at Ser-521, promoting cytoplasmic accumulation and preventing nuclear translocation. S521A mutation leads to constitutive nuclear localization.

"We found that Bach2 is phosphorylated on S521 via the phosphatidylinositol-3/S6 kinase pathway, and substitution of this site to alanine leads to nuclear accumulation of the protein, indicating that this phosphorylation is important for its subcellular localization."

PMID:22194330

The structure of the Bach2 POZ-domain dimer reveals an intersubunit disulfide bond

X-ray crystal structure of BACH2 BTB/POZ domain (residues 9-129) at 2.1A resolution reveals a homodimer with an intersubunit disulfide bond at Cys-20 that may regulate activity in oxidative stress responses.

"Here, the crystal structure of the human Bach2 POZ domain is reported at 2.1 Å resolution."

PMID:23661758

Networks of bZIP protein-protein interactions diversified over a billion years of evolution

Systematic measurement of bZIP dimerization specificities across seven species including human. Identified BACH2 heterodimeric interactions with small MAF proteins (MAFG, MAFF, MAFK) and BATF3.

"We studied the basic region-leucine zipper (bZIP) transcription factors and quantified bZIP dimerization networks for five metazoan and two single-cell species, measuring interactions in vitro for 2891 protein pairs."

PMID:27052415

The Bach Family of Transcription Factors: A Comprehensive Review.

Comprehensive review of Bach1 and Bach2 transcription factors. Describes BACH2 as repressing target gene expression by forming heterodimers with small Maf proteins. Reviews roles in B cell class-switch recombination, T cell homeostasis, oxidative stress-mediated apoptosis, and innate/adaptive immune responses.

"The transcription factors Bach1 and Bach2, which belong to a basic region-leucine zipper (bZip) family, repress target gene expression by forming heterodimers with small Maf proteins."

PMID:28112733

Site-specific mapping of the human SUMO proteome reveals co-modification with phosphorylation

Identified BACH2 SUMOylation at Lys-382 and Lys-421 by mass spectrometry, suggesting SUMO-dependent regulation of BACH2 activity.

"Here we used an augmented K0-SUMO proteomics strategy to identify 40,765 SUMO acceptor sites and quantify their fractional contribution for 6,747 human proteins."

PMID:28473536

Impact of cytosine methylation on DNA binding specificities of human transcription factors

Systematic SELEX analysis of 542 human TFs including BACH2. Demonstrated sequence-specific double-stranded DNA binding by BACH2 and characterized binding specificities including effects of CpG methylation.

"By analysis of 542 human TFs with methylation-sensitive SELEX (systematic evolution of ligands by exponential enrichment), we found that there are also many TFs that prefer CpG-methylated sequences."

PMID:28514442

Architecture of the human interactome defines protein communities and disease networks

BioPlex 2.0 AP-MS study identifying BACH2 protein interactions including with FOSL2, BATF3, MAFF, and TULP3 among others.

"Here we present BioPlex 2.0 (Biophysical Interactions of ORFeome-derived complexes), which uses robust affinity purification-mass spectrometry methodology to elucidate protein interaction networks and co-complexes nucleated by more than 25% of protein-coding genes from the human genome"

PMID:28530713

BACH2 immunodeficiency illustrates an association between super-enhancers and haploinsufficiency

Characterized human BACH2 haploinsufficiency (BRIDA/IMD60) caused by heterozygous variants L24P and E788K. Patients showed intestinal inflammation, recurrent infections, impaired lymphocyte maturation, and decreased immunoglobulin production. Demonstrated BACH2 is a key regulator of adaptive immunity and Treg/B cell function.

"Here we describe a syndrome of BACH2-related immunodeficiency and autoimmunity (BRIDA) that results from BACH2 haploinsufficiency. Affected subjects had lymphocyte-maturation defects that caused immunoglobulin deficiency and intestinal inflammation."

PMID:32296183

A reference map of the human binary protein interactome

HuRI reference interactome identifying binary protein interactions for BACH2 including canonical partners (MAFG, MAFK, MAFF) and many other proteins.

"Here we present a human 'all-by-all' reference interactome map of human binary protein interactions, or 'HuRI'. With approximately 53,000 protein-protein interactions, HuRI has approximately four times as many such interactions as there are high-quality curated interactions from small-scale studies."

PMID:33961781

Dual proteome-scale networks reveal cell-specific remodeling of the human interactome

BioPlex 3.0 interactome study confirming BACH2 interactions with small MAF proteins and other transcription factors.

"Here we present BioPlex 3.0, the most complete model of the human interactome to date, accompanied by a second interaction network acquired in HCT116 cells."

PMID:40205054

Multimodal cell maps as a foundation for structural and functional genomics

Multimodal cell mapping confirming BACH2-MAFK interaction.

"Here we construct a global map of human subcellular architecture through joint measurement of biophysical interactions and immunofluorescence images for over 5,100 proteins in U2OS osteosarcoma cells."

Deep Research

Falcon

(BACH2-deep-research-falcon.md)

this with annotations you find in gene/protein databases, but these can be outdated or inaccurate. Falcon Edison Scientific Literature 10 citations 2026-02-14T14:24:08.233362

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

Plan summary
- Verified the target as human BACH2 (UniProt Q9BYV9) and aligned domains/family with current literature. Searched 2023–2024 sources prioritizing authoritative reviews and recent mechanistic reports. Extracted evidence on molecular function, localization, pathways, immune roles, human genetics, and translational applications, focusing on precise mechanisms and human relevance. Created a tabular artifact summarizing key findings and sources.

Comprehensive research report on human BACH2 (UniProt: Q9BYV9)

Gene/protein verification and identity
BACH2 is the human BTB and CNC homologue 2, a cap’n’collar-type basic leucine zipper (CNC-bZIP) transcription factor with an N-terminal BTB/POZ domain and a C-terminal bZIP DNA-binding/dimerization domain. It forms homo- and heterodimers (notably with small MAF proteins MAFF/MAFG/MAFK) to bind MARE elements and primarily functions as a transcriptional repressor in lymphocytes. These features align with UniProt Q9BYV9 and the bZIP/CNC subfamily classification and BTB/POZ and bZIP domain architecture (Nature Reviews Immunology, 2023; Cells, 2024) (trujilloochoa2023theroleof pages 4-6, zwick2024bach2thefuture pages 1-3).

Key concepts and definitions with current understanding
- Core molecular function: BACH2 is a lineage-defining transcriptional regulator that represses effector differentiation programs by limiting AP-1 access to enhancers and by binding MARE motifs with small MAF partners. In T cells, it stabilizes regulatory programs and promotes stem-like/memory fates; in B cells, it supports germinal-center (GC) functions and class-switch recombination (Nature Reviews Immunology, 2023; Cells, 2024) (trujilloochoa2023theroleof pages 4-6, zwick2024bach2thefuture pages 3-5).
- Domain-functional map: BTB/POZ domain mediates protein–protein interactions and recruitment of corepressors; bZIP mediates DNA binding and dimerization with small MAFs. A C-terminal nuclear export sequence (NES) and nuclear localization determinants regulate nucleocytoplasmic shuttling (Cells, 2024) (zwick2024bach2thefuture pages 1-3, zwick2024bach2thefuture pages 3-5).

Recent developments and latest research (2023–2024 focus)
- Treg identity and stability: Authoritative review integrates recent mechanistic work showing BACH2 restrains effector Treg (eTreg) programs, enforces quiescence of resting Treg cells, and binds the FOXP3 promoter in TGF-β–induced human iTregs; downregulation allows effector/wound-healing genes (Nature Reviews Immunology, 2023; URL: https://doi.org/10.1038/s41577-023-00893-7, Jun 2023) (trujilloochoa2023theroleof pages 4-6, trujilloochoa2023theroleof pages 20-21).
- Post-translational and localization control: 2024 synthesis highlights that PI3K→AKT phosphorylation drives cytoplasmic accumulation, while oxidative stress and SENP3-mediated deSUMOylation favor nuclear retention; a key phosphosite controls localization and function. The review compiles data linking phosphorylation (including B-cell studies) and SUMOylation to nuclear export/import (Cells, 2024; URL: https://doi.org/10.3390/cells13110891, May 2024) (zwick2024bach2thefuture pages 3-5, zwick2024bach2thefuture pages 8-9, zwick2024bach2thefuture pages 12-13).
- CD8+ T cell state control: Recent summaries emphasize BACH2’s role in enforcing stem-like CD8+ states by restricting AP-1 access, shaping chromatin, and opposing premature terminal effector/exhaustion, with implications for chronic stimulation settings (Nature Reviews Immunology, 2023; Cells, 2024) (trujilloochoa2023theroleof pages 20-21, trujilloochoa2023theroleof pages 4-6).

Cellular localization and regulation
- Nucleocytoplasmic shuttling: BACH2 shuttles between nucleus and cytoplasm via a C-terminal NES and nuclear localization determinants. AKT-dependent phosphorylation promotes cytoplasmic localization; oxidative stress and deSUMOylation by SENP3 prevent nuclear export and increase nuclear BACH2 (Cells, 2024; Nature Reviews Immunology, 2023) (zwick2024bach2thefuture pages 3-5, trujilloochoa2023theroleof pages 20-21).
- Signal integration: Metabolic and signaling pathways (PKCβ→mTOR, PI3K→AKT) modulate BACH2 activity and localization; these pathways tune effector restraint versus differentiation in lymphocytes (Cells, 2024) (zwick2024bach2thefuture pages 8-9, zwick2024bach2thefuture pages 3-5).

Primary biological roles and precise functions
- B cells (primary GC functions): BACH2 is required for efficient class-switch recombination (CSR) and for maintaining GC programs while restraining PRDM1/Blimp-1-driven plasma-cell differentiation, thereby promoting memory B cell fate. Mechanistically, it binds and represses effector/PC genes and competes with AP-1 factors on target enhancers (Nature Reviews Immunology, 2023; URL above) (trujilloochoa2023theroleof pages 4-6).
- CD4+ Treg lineage and function: BACH2 represses broad effector transcriptional programs to maintain Treg identity and homeostasis; loss impairs TGF-β–induced iTreg generation and leads to systemic autoimmunity in mouse models. In human iTregs (umbilical cord blood), BACH2 binds FOXP3 promoter and supports stability (Nature Reviews Immunology, 2023; Cells, 2024) (trujilloochoa2023theroleof pages 4-6, zwick2024bach2thefuture pages 1-3).
- CD8+ T cell differentiation: BACH2 promotes stem-like/memory differentiation, restricts terminal effector differentiation, and shapes enhancer access by AP-1, preserving functionality during persistent antigen exposure (Nature Reviews Immunology, 2023; Cells, 2024) (trujilloochoa2023theroleof pages 20-21, trujilloochoa2023theroleof pages 4-6).

Pathways and molecular interactors
- Dimerization partners and DNA elements: small MAFs (MAFF/MAFG/MAFK) are canonical partners; BACH2 binds MARE motifs and competes with AP-1 (e.g., JUND) at enhancers (Nature Reviews Immunology, 2023) (trujilloochoa2023theroleof pages 4-6).
- Transcriptional network in lymphocytes: Interacts functionally with IRF4 and PRDM1/Blimp-1 in B-cell programs; restrains genes such as Jun, Prdm1, Gata3, Irf4, Nfil3, Ahr, Gzmb in T cells to hold effector programs in check (Nature Reviews Immunology, 2023) (trujilloochoa2023theroleof pages 4-6).
- Signaling crosstalk: PTEN–AKT axis and mTOR/PKCβ pathways modulate BACH2 activity and nuclear residence; oxidative stress and SUMO/SENP3 rewire localization and iTreg stability (Cells, 2024) (zwick2024bach2thefuture pages 8-9, zwick2024bach2thefuture pages 3-5).

Genetic evidence in human disease
- Mendelian: BACH2 haploinsufficiency (BACH2-related immunodeficiency and autoimmunity, BRIDA) causes immune dysregulation with autoimmunity and features of immunodeficiency. Reviews collate human coding variant reports and super-enhancer dysregulation at the BACH2 locus (Cells, 2024; Nature Reviews Immunology, 2023) (zwick2024bach2thefuture pages 12-13, trujilloochoa2023theroleof pages 4-6).
- Common variant associations: GWAS/meta-analyses consistently implicate BACH2 in autoimmune susceptibility, including type 1 diabetes, Crohn’s disease, celiac disease, rheumatoid arthritis, multiple sclerosis, asthma, vitiligo, and autoimmune thyroid disease. Specific SLE-associated variant rs597325 is highlighted in compilations (Nature Reviews Immunology, 2023; Cells, 2024) (trujilloochoa2023theroleof pages 4-6, zwick2024bach2thefuture pages 12-13).

Current applications and real-world implementations
- iTreg therapy optimization: Reviews propose stabilizing BACH2 during human iTreg manufacturing to overcome instability and enhance suppressive potency; mesenchymal stromal cell co-culture and redox/SUMO pathway modulation are discussed as strategies to maintain nuclear BACH2 and FOXP3 stability (Cells, 2024; URL above) (zwick2024bach2thefuture pages 8-9, zwick2024bach2thefuture pages 1-3).
- T cell therapy engineering: Conceptual and preclinical frameworks position BACH2 as a “memory transcription factor” to be dosed/tuned to preserve stem-like states and counter exhaustion in engineered T cells (e.g., CAR-T) under chronic antigen exposure, while acknowledging safety/lineage control considerations (Negrin thesis 2026; synthesis in 2024 review) (negrin2026enhancingtcella pages 34-37, trujilloochoa2023theroleof pages 20-21).

Expert opinions and analysis from authoritative sources
- Nature Reviews Immunology (2023) synthesizes primary evidence to position BACH2 as a central regulator of Treg identity, a gatekeeper of quiescence, and a broad repressor of effector programs across T cells, with extensive GWAS support for autoimmunity. It emphasizes AP-1 competition, FOXP3 promoter binding in iTregs, and chromatin-level control in CD8+ T cell fates (Nature Reviews Immunology, 2023) (trujilloochoa2023theroleof pages 4-6, trujilloochoa2023theroleof pages 20-21).
- The 2024 Cells review argues for BACH2 as a master regulator whose activity is exquisitely sensitive to activation and metabolic state, highlighting PTM control (phosphorylation, SUMO) and proposing actionable levers to enhance iTreg therapy. It compiles human genetic links including BRIDA and broad autoimmune associations (Cells, 2024) (zwick2024bach2thefuture pages 3-5, zwick2024bach2thefuture pages 12-13, zwick2024bach2thefuture pages 8-9, zwick2024bach2thefuture pages 1-3).

Relevant statistics and data from recent studies
- Human genetics breadth: Compilations in 2023–2024 reviews list multiple autoimmune GWAS signals at BACH2 (e.g., T1D, Crohn’s, MS, celiac, RA, vitiligo, AITD), indicating pleiotropic autoimmunity risk mediated by BACH2 locus variation; specific SLE-associated SNP rs597325 is cited (Nature Reviews Immunology, 2023; Cells, 2024) (trujilloochoa2023theroleof pages 4-6, zwick2024bach2thefuture pages 12-13). While these sources aggregate findings, they do not provide single-study cohort n/effect sizes within the cited pages; they nevertheless indicate convergent multi-disease evidence.
- Mechanistic localization control: The 2024 synthesis specifies that PI3K–AKT phosphorylation biases cytoplasmic localization, while oxidative stress and SENP3-mediated deSUMOylation block nuclear export and enhance nuclear accumulation—mechanistically supporting intervention points for cell-therapy manufacturing (Cells, 2024) (zwick2024bach2thefuture pages 3-5, zwick2024bach2thefuture pages 8-9).

Limitations and scope
- Most mechanistic precision for enhancer competition, chromatin regulation, and T cell lineage control integrates mouse and human evidence; the cited 2023–2024 reviews clearly demarcate human relevance where available. Where quantitative GWAS effect sizes or cohort counts are not enumerated in the review excerpts, we report convergent disease links rather than specific statistics (trujilloochoa2023theroleof pages 4-6, zwick2024bach2thefuture pages 12-13).

Embedded summary artifact
| Aspect | Summary & sources |
|---|---|
| Identity / Domains | • BTB/POZ N‑terminal domain; C‑terminal basic‑region leucine‑zipper (bZIP); heterodimerizes with small MAF proteins; lymphoid‑enriched, ≈92 kDa. Sources: Zwick et al. 2024 https://doi.org/10.3390/cells13110891; Trujillo‑Ochoa et al. 2023 https://doi.org/10.1038/s41577-023-00893-7 (zwick2024bach2thefuture pages 3-5, trujilloochoa2023theroleof pages 20-21) |
| Molecular mechanism | • Transcriptional repressor at MARE motifs; limits AP‑1 access to enhancers (competitive repression). • Regulated by PTMs: phosphorylation (PI3K→AKT) and SUMO/SENP3 control nuclear export/retention and activity. Sources: Zwick et al. 2024 https://doi.org/10.3390/cells13110891; Trujillo‑Ochoa et al. 2023 https://doi.org/10.1038/s41577-023-00893-7 (zwick2024bach2thefuture pages 3-5, trujilloochoa2023theroleof pages 20-21) |
| Primary immune roles | • B cells: enforces germinal‑center programs, restrains premature plasma‑cell differentiation, required for class‑switch recombination and memory B cell fate. • T cells: stabilizes FOXP3+ iTreg phenotype and represses effector programs; in CD8+ T cells promotes stem‑like/memory states and limits terminal effector/exhaustion. Sources: Trujillo‑Ochoa et al. 2023 https://doi.org/10.1038/s41577-023-00893-7; Zwick et al. 2024 https://doi.org/10.3390/cells13110891 (trujilloochoa2023theroleof pages 20-21, zwick2024bach2thefuture pages 3-5) |
| Subcellular localization & regulation | • Nucleus↔cytoplasm shuttling via NES/NLS; phosphorylation (PI3K→AKT) favors cytoplasmic localization. • Oxidative stress and SUMO/SENP3‑mediated regulation promote nuclear retention and functional switching. Sources: Zwick et al. 2024 https://doi.org/10.3390/cells13110891; Trujillo‑Ochoa et al. 2023 https://doi.org/10.1038/s41577-023-00893-7 (zwick2024bach2thefuture pages 3-5, trujilloochoa2023theroleof pages 20-21) |
| Key pathways & interactors | • Partners/targets: small MAFs (MAFF/MAFG/MAFK), IRF4, PRDM1/Blimp‑1; competes with AP‑1 factors at enhancers. • Linked signaling: PTEN→AKT (metabolic control) and mTOR/PKC axes affecting BACH2 activity. Sources: Trujillo‑Ochoa et al. 2023 https://doi.org/10.1038/s41577-023-00893-7; Zwick et al. 2024 https://doi.org/10.3390/cells13110891 (trujilloochoa2023theroleof pages 20-21, zwick2024bach2thefuture pages 3-5) |
| Human genetics & disease links | • Mendelian: heterozygous BACH2 loss (haploinsufficiency / BRIDA) → immune dysregulation with autoimmunity and immunodeficiency. • Common‑variant: GWAS associations across autoimmune diseases (T1D, Crohn's, MS, vitiligo, autoimmune thyroid disease, etc.). Sources: Zwick et al. 2024 https://doi.org/10.3390/cells13110891; Trujillo‑Ochoa et al. 2023 https://doi.org/10.1038/s41577-023-00893-7 (zwick2024bach2thefuture pages 3-5, trujilloochoa2023theroleof pages 20-21) |
| Translational / clinical applications | • iTreg cell therapy: increasing/stabilizing BACH2 proposed to improve iTreg stability and suppressive function during manufacture. • T cell engineering/CAR‑T: dosage/timing tuning of BACH2 to preserve memory/stem‑like states and improve persistence in chronic antigen settings (preclinical/strategic proposals). Sources: Zwick et al. 2024 https://doi.org/10.3390/cells13110891; Negrin 2026 discussion (T‑cell dosing concept) (zwick2024bach2thefuture pages 3-5, negrin2026enhancingtcella pages 34-37) |

Table: Concise, evidence‑linked table summarizing human BACH2 (UniProt Q9BYV9) covering domains, mechanism, immune roles, localization, interactors, genetic links, and translational applications with source URLs and evidence IDs.

Conclusion
Human BACH2 (Q9BYV9) is a CNC-bZIP transcriptional regulator with BTB/POZ and bZIP domains that dimerizes with small MAFs to bind MAREs and broadly represses AP‑1–driven effector programs. It integrates metabolic and signaling inputs (PI3K–AKT, mTOR, oxidative/SUMO) via PTMs to control nuclear localization and activity. In B cells, it is required for GC integrity and CSR while restraining plasma-cell differentiation; in T cells, it stabilizes FOXP3+ Tregs and enforces stem-like/memory CD8+ states that resist terminal exhaustion. Human genetics links haploinsufficiency (BRIDA) and common variants at BACH2 to multiple autoimmune diseases. Recent 2023–2024 analyses converge on translational strategies to modulate BACH2—particularly to stabilize iTregs and tune engineered T cells under chronic antigen—to enhance clinical efficacy while preserving safety (trujilloochoa2023theroleof pages 4-6, trujilloochoa2023theroleof pages 20-21, zwick2024bach2thefuture pages 3-5, zwick2024bach2thefuture pages 8-9, zwick2024bach2thefuture pages 12-13, zwick2024bach2thefuture pages 1-3, negrin2026enhancingtcella pages 34-37, negrin2026enhancingtcell pages 34-37).

References

(trujilloochoa2023theroleof pages 4-6): Jorge L. Trujillo-Ochoa, Majid Kazemian, and Behdad Afzali. The role of transcription factors in shaping regulatory t cell identity. Nature Reviews Immunology, 23:842-856, Jun 2023. URL: https://doi.org/10.1038/s41577-023-00893-7, doi:10.1038/s41577-023-00893-7. This article has 111 citations and is from a highest quality peer-reviewed journal.
(zwick2024bach2thefuture pages 1-3): Daniel Zwick, Mai Tram Vo, Young Jun Shim, Helena Reijonen, and Jeong-su Do. Bach2: the future of induced t-regulatory cell therapies. Cells, 13:891, May 2024. URL: https://doi.org/10.3390/cells13110891, doi:10.3390/cells13110891. This article has 8 citations and is from a poor quality or predatory journal.
(zwick2024bach2thefuture pages 3-5): Daniel Zwick, Mai Tram Vo, Young Jun Shim, Helena Reijonen, and Jeong-su Do. Bach2: the future of induced t-regulatory cell therapies. Cells, 13:891, May 2024. URL: https://doi.org/10.3390/cells13110891, doi:10.3390/cells13110891. This article has 8 citations and is from a poor quality or predatory journal.
(trujilloochoa2023theroleof pages 20-21): Jorge L. Trujillo-Ochoa, Majid Kazemian, and Behdad Afzali. The role of transcription factors in shaping regulatory t cell identity. Nature Reviews Immunology, 23:842-856, Jun 2023. URL: https://doi.org/10.1038/s41577-023-00893-7, doi:10.1038/s41577-023-00893-7. This article has 111 citations and is from a highest quality peer-reviewed journal.
(zwick2024bach2thefuture pages 8-9): Daniel Zwick, Mai Tram Vo, Young Jun Shim, Helena Reijonen, and Jeong-su Do. Bach2: the future of induced t-regulatory cell therapies. Cells, 13:891, May 2024. URL: https://doi.org/10.3390/cells13110891, doi:10.3390/cells13110891. This article has 8 citations and is from a poor quality or predatory journal.
(zwick2024bach2thefuture pages 12-13): Daniel Zwick, Mai Tram Vo, Young Jun Shim, Helena Reijonen, and Jeong-su Do. Bach2: the future of induced t-regulatory cell therapies. Cells, 13:891, May 2024. URL: https://doi.org/10.3390/cells13110891, doi:10.3390/cells13110891. This article has 8 citations and is from a poor quality or predatory journal.
(negrin2026enhancingtcella pages 34-37): A Conti Negrin. Enhancing t cell immunotherapy through dosing of memory transcription factors. Unknown journal, 2026.
(negrin2026enhancingtcell pages 34-37): A Conti Negrin. Enhancing t cell immunotherapy through dosing of memory transcription factors. Unknown journal, 2026.

Citations

trujilloochoa2023theroleof pages 4-6
trujilloochoa2023theroleof pages 20-21
negrin2026enhancingtcella pages 34-37
negrin2026enhancingtcell pages 34-37
https://doi.org/10.1038/s41577-023-00893-7,
https://doi.org/10.3390/cells13110891,
https://doi.org/10.3390/cells13110891;
https://doi.org/10.1038/s41577-023-00893-7
https://doi.org/10.1038/s41577-023-00893-7;
https://doi.org/10.3390/cells13110891

📄 View Raw YAML

id: Q9BYV9
gene_symbol: BACH2
product_type: PROTEIN
status: DRAFT
taxon:
  id: NCBITaxon:9606
  label: Homo sapiens
description: BACH2 (BTB and CNC homolog 2) is a CNC-bZIP transcription factor that
  functions primarily as a transcriptional repressor in B and T lymphocytes. It contains
  an N-terminal BTB/POZ domain that mediates homodimerization and protein-protein
  interactions, and a C-terminal bZIP domain through which it heterodimerizes with
  small MAF proteins (MAFF, MAFG, MAFK) to bind Maf recognition elements (MAREs) in
  DNA. In B cells, BACH2 maintains the germinal center program by repressing PRDM1
  (Blimp-1), thereby preventing premature plasma cell differentiation and supporting
  class-switch recombination. In T cells, BACH2 stabilizes regulatory T cell (Treg)
  identity by repressing effector gene programs and promotes stem-like/memory CD8+
  T cell fates by competing with AP-1 factors at enhancers. BACH2 undergoes regulated
  nucleocytoplasmic shuttling controlled by PI3K-AKT-dependent phosphorylation at
  Ser-521 (promoting cytoplasmic localization) and by oxidative stress and SUMOylation
  (promoting nuclear retention). Haploinsufficiency of BACH2 causes BACH2-related
  immunodeficiency and autoimmunity (BRIDA/IMD60), and common GWAS variants at the
  BACH2 locus are associated with multiple autoimmune diseases including type 1 diabetes,
  multiple sclerosis, celiac disease, and Crohn disease.
existing_annotations:
- term:
    id: GO:0006357
    label: regulation of transcription by RNA polymerase II
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: IBA annotation placing BACH2 as a regulator of RNA Pol II transcription,
      inferred from phylogenetic analysis of the CNC-bZIP family. BACH2 is a well-established
      transcriptional regulator that binds MARE elements as a heterodimer with small
      MAF proteins and modulates Pol II-dependent gene expression in lymphocytes (PMID:28530713,
      PMID:27052415).
    action: ACCEPT
    reason: This is a core function of BACH2. As a bZIP transcription factor, it directly
      regulates Pol II-dependent transcription. The IBA annotation is well supported
      by the phylogenetic relationship of BACH2 to other CNC-bZIP family members (NRF2,
      BACH1, NFE2L1) that all regulate Pol II transcription. The annotation is at
      the right level of generality for an IBA inference since BACH2 can act as both
      repressor and (in some contexts) activator.
    supported_by:
    - reference_id: PMID:17018862
      supporting_text: we showed that Bach2 transcriptionally represses heme oxygenase-1,
        an antiapoptotic factor up-regulated in CML
    - reference_id: PMID:28530713
      supporting_text: BACH2 is a typical example of an SE-regulated gene associated
        with autoimmune disease. It is a highly conserved member of the basic and
        leucine zipper domain (bZIP) superfamily of TFs and a critical regulator of
        both T and B lymphocyte differentiation and maturation
- term:
    id: GO:0000978
    label: RNA polymerase II cis-regulatory region sequence-specific DNA binding
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: IBA annotation for sequence-specific DNA binding at Pol II cis-regulatory
      regions. BACH2 contains a bZIP DNA-binding domain (residues 646-709) and binds
      MARE motifs (TRE/CRE-like sequences with flanking TGC) as a heterodimer with
      small MAF proteins. This has been demonstrated by SELEX (PMID:28473536) and
      is consistent with its role as a sequence-specific DNA-binding transcription
      factor.
    action: ACCEPT
    reason: BACH2 has a characterized bZIP DNA-binding domain and binds specific DNA
      sequences (MARE elements) at regulatory regions. The IBA annotation is phylogenetically
      consistent and directly supported by experimental evidence showing sequence-specific
      DNA binding via SELEX analysis (PMID:28473536).
    supported_by:
    - reference_id: PMID:28473536
      supporting_text: By analysis of 542 human TFs with methylation-sensitive SELEX
        (systematic evolution of ligands by exponential enrichment), we found that
        there are also many TFs that prefer CpG-methylated sequences
- term:
    id: GO:0000981
    label: DNA-binding transcription factor activity, RNA polymerase II-specific
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: IBA annotation for DNA-binding transcription factor activity (Pol II-specific).
      BACH2 is a bona fide sequence-specific DNA-binding transcription factor that
      modulates Pol II transcription. It primarily acts as a transcriptional repressor,
      though it can also activate transcription in some contexts (UniProt, by similarity).
      Given BACH2's predominant repressor function, a more specific child term (GO:0001227,
      DNA-binding transcription repressor activity, RNA polymerase II-specific) would
      be more informative, but the parent term is not wrong.
    action: ACCEPT
    reason: The IBA annotation is correct and at a reasonable level of specificity
      since the phylogenetic inference groups BACH2 with family members that can act
      as both activators and repressors. BACH2 is primarily a repressor but has been
      reported to also activate in some contexts, so the parent term GO:0000981 is
      defensible.
    supported_by:
    - reference_id: PMID:27052415
      supporting_text: The transcription factors Bach1 and Bach2, which belong to
        a basic region-leucine zipper (bZip) family, repress target gene expression
        by forming heterodimers with small Maf proteins
- term:
    id: GO:0003677
    label: DNA binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  review:
    summary: IEA annotation for generic DNA binding based on combined automated methods
      including InterPro domain matches (bZIP, bZIP_Maf) and orthology to mouse BACH2
      (P97303). BACH2 does bind DNA through its bZIP domain, but this term is very
      general and is subsumed by the more specific annotations already present.
    action: ACCEPT
    reason: While overly general, IEA annotations to broad parent terms are acceptable
      when more specific annotations exist. The more specific GO:0000978 (IBA) and
      GO:1990837 (IDA) already capture the DNA binding activity of BACH2 more precisely.
      This IEA annotation is not wrong and will be naturally superseded.
    supported_by:
    - reference_id: PMID:28473536
      supporting_text: By analysis of 542 human TFs with methylation-sensitive SELEX
        (systematic evolution of ligands by exponential enrichment), we found that
        there are also many TFs that prefer CpG-methylated sequences
- term:
    id: GO:0003700
    label: DNA-binding transcription factor activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  review:
    summary: IEA annotation for generic DNA-binding transcription factor activity
      based on InterPro domain matches and orthology. This is the parent of GO:0000981
      which is already annotated via IBA. The annotation is correct but less specific.
    action: ACCEPT
    reason: Correct but general. The more specific GO:0000981 (IBA) already captures
      the Pol II-specific transcription factor activity. This broader IEA term is
      acceptable as a computationally derived parent annotation.
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  review:
    summary: IEA annotation for nuclear localization based on combined automated methods
      including orthology to mouse BACH2 and UniProt subcellular location data. BACH2
      localizes to the nucleus where it functions as a transcriptional repressor.
      Nuclear localization is experimentally confirmed (PMID:17018862, PMID:28530713)
      and noted in UniProt.
    action: ACCEPT
    reason: Correct. BACH2 functions in the nucleus as a transcription factor. UniProt
      confirms nuclear localization supported by experimental evidence from PMID:17018862
      and PMID:28530713. BACH2 undergoes regulated nucleocytoplasmic shuttling, but
      the nucleus is a primary functional location.
    supported_by:
    - reference_id: PMID:17018862
      supporting_text: Bach2 is phosphorylated on S521 via the phosphatidylinositol-3/S6
        kinase pathway, and substitution of this site to alanine leads to nuclear
        accumulation of the protein, indicating that this phosphorylation is important
        for its subcellular localization
    - reference_id: PMID:28530713
      supporting_text: BACH2 dimers translocate to the nucleus where they interact
        with target DNA loci at palindromic Maf recognition elements (MARE), either
        alone or in collaboration with other members of the bZIP family, such as the
        small Maf proteins (MafF, MafG and MafK)
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  review:
    summary: IEA annotation for cytoplasmic localization based on UniProt subcellular
      location vocabulary mapping. UniProt lists cytoplasm as a subcellular location
      for BACH2, supported by experimental evidence showing that PI3K-AKT-dependent
      phosphorylation at Ser-521 promotes cytoplasmic accumulation (PMID:17018862).
      BACH2 also forms cytoplasmic aggregates when mutated (E788K variant in IMD60).
    action: ACCEPT
    reason: Correct. BACH2 undergoes regulated nucleocytoplasmic shuttling. Phosphorylation
      at Ser-521 downstream of the PI3K pathway promotes cytoplasmic localization
      (PMID:17018862). The cytoplasm is a bona fide subcellular location for BACH2,
      particularly in its inactive/phosphorylated state.
    supported_by:
    - reference_id: PMID:17018862
      supporting_text: Bach2 is phosphorylated on S521 via the phosphatidylinositol-3/S6
        kinase pathway, and substitution of this site to alanine leads to nuclear
        accumulation of the protein, indicating that this phosphorylation is important
        for its subcellular localization
    - reference_id: PMID:28530713
      supporting_text: we found that wild-type BACH2 protein was evenly distributed
        in both cytoplasm and nucleus, whereas the E788K mutant protein was aggregated
        in the cytoplasm with relatively little in the nucleus
- term:
    id: GO:0006355
    label: regulation of DNA-templated transcription
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  review:
    summary: IEA annotation for regulation of DNA-templated transcription based on
      InterPro domain associations (bZIP, bZIP_Maf, TF_DNA-bd domains). This is a
      parent term of GO:0006357 (regulation of transcription by RNA polymerase II)
      which is already annotated via IBA.
    action: ACCEPT
    reason: Correct but more general than GO:0006357 already captured by IBA. As an
      IEA derived from domain associations, this broad annotation is acceptable and
      will be naturally superseded by the more specific annotations.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:23661758
  review:
    summary: 'IPI annotation for protein binding based on the Reinke et al. 2013 study
      that systematically measured bZIP dimerization networks across species. The
      with/from fields indicate interactions with MAFG (O15525), BATF3 (Q9NR55), and
      MAFF (Q9ULX9). These are biologically meaningful interactions: small MAF proteins
      are the canonical dimerization partners of BACH2 for DNA binding, and BATF3
      is a bZIP family member. However, ''protein binding'' is uninformative.'
    action: MODIFY
    reason: The interactions with MAFG, MAFF, and BATF3 are biologically relevant
      dimerization events for a bZIP transcription factor. However, GO:0005515 (protein
      binding) is uninformative per GO curation guidelines. The actual function is
      DNA-binding transcription factor activity enabled by dimerization with small
      MAF proteins. The protein-protein interactions are integral to the transcription
      factor activity and are better captured by the ComplexPortal entries (CPX-2484
      for BACH2-MAFF, CPX-2485 for BACH2-MAFG).
    proposed_replacement_terms:
    - id: GO:0042803
      label: protein homodimerization activity
    - id: GO:0046982
      label: protein heterodimerization activity
    supported_by:
    - reference_id: PMID:23661758
      supporting_text: We studied the basic region-leucine zipper (bZIP) transcription
        factors and quantified bZIP dimerization networks for five metazoan and two
        single-cell species, measuring interactions in vitro for 2891 protein pairs
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:28514442
  review:
    summary: IPI annotation for protein binding based on BioPlex 2.0 high-throughput
      AP-MS study (Huttlin et al. 2017). The with/from fields include TULP3 (O75386),
      FOSL2 (P15408), BATF3 (Q9NR55), and MAFF (Q9ULX9). The interactions with FOSL2
      (an AP-1 factor) and small MAFs are biologically meaningful for a bZIP TF, but
      TULP3 interaction is likely from high-throughput noise.
    action: MODIFY
    reason: High-throughput AP-MS data. Some interactors (FOSL2, BATF3, MAFF) are
      biologically plausible bZIP dimerization partners. Others (TULP3) may be spurious.
      GO:0005515 is uninformative per curation guidelines.
    proposed_replacement_terms:
    - id: GO:0046982
      label: protein heterodimerization activity
    supported_by:
    - reference_id: PMID:28514442
      supporting_text: Architecture of the human interactome defines protein communities
        and disease networks
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:32296183
  review:
    summary: IPI annotation for protein binding based on the HuRI reference binary
      interactome study (Luck et al. 2020). This study identified numerous interaction
      partners including MAFG (O15525), MAFK (O60675), FOSL2 (P15408), BATF3 (Q9NR55),
      and many other proteins. The MAF/BATF3 interactions are biologically meaningful
      as canonical bZIP dimerization partners. Many others (CTSZ, CENPP, CFAP58, etc.)
      are likely high-throughput artifacts.
    action: MODIFY
    reason: Large-scale binary interactome study. GO:0005515 is uninformative. The
      meaningful interactions (with MAF proteins and bZIP family members) reflect
      heterodimerization activity integral to transcription factor function.
    proposed_replacement_terms:
    - id: GO:0046982
      label: protein heterodimerization activity
    supported_by:
    - reference_id: PMID:32296183
      supporting_text: A reference map of the human binary protein interactome
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:33961781
  review:
    summary: IPI annotation for protein binding based on BioPlex 3.0 (Huttlin et al.
      2021). Interactors include MAFG (O15525), MAFK (O60675), MAFF (Q9ULX9), FOSL2
      (P15408), BATF3 (Q9NR55), ZBTB24, and ZBTB34. The MAF interactions are canonical
      and biologically validated.
    action: MODIFY
    reason: Proteome-scale interactome study. GO:0005515 is uninformative per curation
      guidelines. The biologically meaningful interactions are bZIP dimerization with
      small MAFs and other bZIP family members.
    proposed_replacement_terms:
    - id: GO:0046982
      label: protein heterodimerization activity
    supported_by:
    - reference_id: PMID:33961781
      supporting_text: Dual proteome-scale networks reveal cell-specific remodeling
        of the human interactome
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:40205054
  review:
    summary: IPI annotation for protein binding from multimodal cell maps study (Schaffer
      et al. 2025). The with/from field indicates interaction with MAFK (O60675),
      a canonical small MAF dimerization partner of BACH2.
    action: MODIFY
    reason: GO:0005515 is uninformative. The MAFK interaction is a canonical bZIP
      heterodimerization that is integral to BACH2's transcription factor function.
    proposed_replacement_terms:
    - id: GO:0046982
      label: protein heterodimerization activity
    supported_by:
    - reference_id: PMID:40205054
      supporting_text: Multimodal cell maps as a foundation for structural and functional
        genomics
- term:
    id: GO:0000122
    label: negative regulation of transcription by RNA polymerase II
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  review:
    summary: IEA annotation transferred from mouse ortholog (P97303) via Ensembl Compara.
      BACH2 is well established as a transcriptional repressor. It represses PRDM1
      (Blimp-1) to maintain germinal center programs in B cells, and represses effector
      gene programs (Gata3, Irf4, Prdm1, Gzmb) in T cells. The mouse ortholog has
      extensive experimental evidence for transcriptional repression.
    action: ACCEPT
    reason: Correct and central to BACH2 biology. BACH2 is predominantly a transcriptional
      repressor. PMID:17018862 shows repression of HMOX1, and PMID:28530713 shows
      BACH2 represses PRDM1 to control B cell differentiation. This IEA from Ensembl
      Compara is well supported by the biology.
    supported_by:
    - reference_id: PMID:17018862
      supporting_text: we showed that Bach2 transcriptionally represses heme oxygenase-1,
        an antiapoptotic factor up-regulated in CML
    - reference_id: PMID:28530713
      supporting_text: In B cells, BACH2 controls the balance between Pax5 and Blimp1
        by repressing the latter
- term:
    id: GO:0000978
    label: RNA polymerase II cis-regulatory region sequence-specific DNA binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  review:
    summary: IEA annotation transferred from mouse ortholog via Ensembl Compara. Duplicates
      the IBA annotation for the same term. BACH2 does bind DNA in a sequence-specific
      manner at Pol II-regulated genes.
    action: ACCEPT
    reason: Correct and consistent with the IBA annotation for the same term. Duplication
      of evidence from different sources (IBA and IEA) is normal and acceptable.
- term:
    id: GO:0001227
    label: DNA-binding transcription repressor activity, RNA polymerase II-specific
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  review:
    summary: IEA annotation for transcription repressor activity transferred from
      mouse ortholog via Ensembl Compara. This is the most specific and accurate molecular
      function term for BACH2, which primarily functions as a DNA-binding transcriptional
      repressor at MARE elements in Pol II-transcribed genes.
    action: ACCEPT
    reason: This is the most accurate MF term for BACH2's primary molecular function.
      BACH2 predominantly represses transcription by binding MARE elements as a heterodimer
      with small MAF proteins. It represses PRDM1/Blimp-1 in B cells and effector
      gene programs in T cells. Per GO TF annotation guidelines, a child of GO:0000981
      specifying repressor activity is the ideal annotation for a predominantly repressive
      DNA-binding transcription factor.
    supported_by:
    - reference_id: PMID:17018862
      supporting_text: we showed that Bach2 transcriptionally represses heme oxygenase-1,
        an antiapoptotic factor up-regulated in CML
    - reference_id: PMID:28530713
      supporting_text: BACH2 acts as a repressive "guardian" TF that regulates the
        balance between a network of other TFs critical to T and B cell specification
        and maturation
- term:
    id: GO:0005654
    label: nucleoplasm
  evidence_type: IDA
  original_reference_id: GO_REF:0000052
  review:
    summary: IDA annotation for nucleoplasm localization based on HPA immunofluorescence
      data curation. BACH2 functions in the nucleoplasm as a transcription factor.
      When in the nucleus, it would be expected to be in the nucleoplasm where it
      accesses chromatin and regulatory DNA elements.
    action: ACCEPT
    reason: Correct. BACH2 is a transcription factor that functions in the nucleoplasm.
      IDA from HPA immunofluorescence is appropriate evidence for subcellular localization.
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: IDA
  original_reference_id: GO_REF:0000052
  review:
    summary: IDA annotation for cytosol localization based on HPA immunofluorescence
      data. BACH2 is known to undergo regulated nucleocytoplasmic shuttling, with
      PI3K-AKT-dependent phosphorylation at Ser-521 promoting cytoplasmic accumulation
      (PMID:17018862). The cytosol is a bona fide localization for the inactive/phosphorylated
      form.
    action: ACCEPT
    reason: Correct. BACH2 accumulates in the cytoplasm/cytosol when phosphorylated
      by the PI3K-AKT pathway. This is more specific than GO:0005737 (cytoplasm) already
      annotated via IEA. HPA immunofluorescence data supports this.
    supported_by:
    - reference_id: PMID:17018862
      supporting_text: Bach2 is phosphorylated on S521 via the phosphatidylinositol-3/S6
        kinase pathway, and substitution of this site to alanine leads to nuclear
        accumulation of the protein, indicating that this phosphorylation is important
        for its subcellular localization
- term:
    id: GO:0000122
    label: negative regulation of transcription by RNA polymerase II
  evidence_type: NAS
  original_reference_id: PMID:27052415
  review:
    summary: NAS annotation from ComplexPortal for negative regulation of Pol II transcription,
      citing PMID:27052415 (Zhou et al. 2016). This review describes how BACH2 represses
      target gene expression by forming heterodimers with small Maf proteins. BACH2's
      primary role as a transcriptional repressor is well documented across multiple
      studies.
    action: ACCEPT
    reason: Correct and well supported. PMID:27052415 is a comprehensive review of
      the Bach family of transcription factors that clearly describes BACH2 as repressing
      target gene expression. The same term is also annotated via IEA from Ensembl
      Compara. Both annotations are correct for this core function of BACH2.
    supported_by:
    - reference_id: PMID:27052415
      supporting_text: The transcription factors Bach1 and Bach2, which belong to
        a basic region-leucine zipper (bZip) family, repress target gene expression
        by forming heterodimers with small Maf proteins
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: NAS
  original_reference_id: PMID:23661758
  review:
    summary: NAS annotation from ComplexPortal for nuclear localization, citing the
      Reinke et al. 2013 bZIP network study. This study characterized bZIP protein-protein
      interactions in vitro and does not directly demonstrate nuclear localization.
      However, nuclear localization is well established for BACH2 from other studies.
    action: ACCEPT
    reason: Nuclear localization of BACH2 is well supported by multiple lines of evidence
      (PMID:17018862, PMID:28530713, UniProt subcellular location). The NAS evidence
      code from ComplexPortal is acceptable since BACH2 functions as a nuclear transcription
      factor in complex with MAF proteins.
    supported_by:
    - reference_id: PMID:28530713
      supporting_text: BACH2 dimers translocate to the nucleus where they interact
        with target DNA loci at palindromic Maf recognition elements (MARE), either
        alone or in collaboration with other members of the bZIP family, such as the
        small Maf proteins (MafF, MafG and MafK)
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: NAS
  original_reference_id: PMID:27052415
  review:
    summary: NAS annotation from ComplexPortal for nuclear localization, citing PMID:27052415
      (Zhou et al. 2016). This review confirms BACH2 is a nuclear transcription factor
      that represses gene expression.
    action: ACCEPT
    reason: Correct. Nuclear localization is well established for BACH2 as a transcription
      factor. PMID:27052415 describes BACH2 as a transcription factor that represses
      target gene expression, which requires nuclear localization. This is consistent
      with the other nuclear localization annotations from IEA, NAS, and IDA evidence.
    supported_by:
    - reference_id: PMID:27052415
      supporting_text: The transcription factors Bach1 and Bach2, which belong to
        a basic region-leucine zipper (bZip) family, repress target gene expression
        by forming heterodimers with small Maf proteins
- term:
    id: GO:0006357
    label: regulation of transcription by RNA polymerase II
  evidence_type: NAS
  original_reference_id: PMID:23661758
  review:
    summary: NAS annotation from ComplexPortal for regulation of Pol II transcription,
      citing the Reinke et al. 2013 bZIP dimerization study. The study demonstrated
      BACH2 forms heterodimers with small MAF proteins and other bZIP factors, consistent
      with regulation of Pol II transcription. This is a duplicate of the IBA annotation
      for the same term.
    action: ACCEPT
    reason: Correct. BACH2 regulates Pol II transcription as a bZIP transcription
      factor. The NAS evidence from ComplexPortal is based on the bZIP dimerization
      data. Same term already captured by IBA with stronger phylogenetic evidence.
    supported_by:
    - reference_id: PMID:23661758
      supporting_text: We studied the basic region-leucine zipper (bZIP) transcription
        factors and quantified bZIP dimerization networks for five metazoan and two
        single-cell species, measuring interactions in vitro for 2891 protein pairs
- term:
    id: GO:1990837
    label: sequence-specific double-stranded DNA binding
  evidence_type: IDA
  original_reference_id: PMID:28473536
  review:
    summary: IDA annotation for sequence-specific double-stranded DNA binding based
      on Yin et al. 2017, a systematic SELEX study of 542 human TFs. BACH2 was among
      the TFs tested, and its binding specificities to double-stranded DNA sequences
      were characterized. This directly demonstrates BACH2 binds specific dsDNA sequences.
    action: ACCEPT
    reason: Strong experimental evidence (IDA from SELEX) directly demonstrating that
      BACH2 binds specific dsDNA sequences. This is consistent with BACH2's bZIP domain
      and its function as a sequence-specific DNA-binding transcription factor that
      recognizes MARE motifs.
    supported_by:
    - reference_id: PMID:28473536
      supporting_text: By analysis of 542 human TFs with methylation-sensitive SELEX
        (systematic evolution of ligands by exponential enrichment), we found that
        there are also many TFs that prefer CpG-methylated sequences
- term:
    id: GO:0090721
    label: primary adaptive immune response involving T cells and B cells
  evidence_type: IMP
  original_reference_id: PMID:28530713
  review:
    summary: IMP annotation for involvement in primary adaptive immune response based
      on Afzali et al. 2017, which characterized human BACH2 haploinsufficiency (BRIDA/IMD60).
      Patients with heterozygous BACH2 variants showed impaired lymphocyte maturation,
      decreased immunoglobulin production, and autoimmunity, demonstrating BACH2 is
      essential for proper adaptive immune responses.
    action: KEEP_AS_NON_CORE
    reason: While BACH2 is clearly required for proper adaptive immune function (as
      demonstrated by the BRIDA phenotype), this is a very broad biological process
      term that describes the downstream consequence of BACH2's transcriptional repressor
      activity rather than its core molecular function. The primary role of BACH2
      is as a DNA-binding transcriptional repressor; its involvement in adaptive immunity
      is a downstream effect of that core function in lymphocytes. Marking as non-core
      since the annotation is correct but represents a broad organismal phenotype
      rather than a core molecular-level function.
    supported_by:
    - reference_id: PMID:28530713
      supporting_text: Here we describe a syndrome of BACH2-related immunodeficiency
        and autoimmunity (BRIDA) that results from BACH2 haploinsufficiency. Affected
        subjects had lymphocyte-maturation defects that caused immunoglobulin deficiency
- term:
    id: GO:0000785
    label: chromatin
  evidence_type: ISA
  original_reference_id: GO_REF:0000113
  review:
    summary: ISA annotation for chromatin localization based on TFClass database annotation
      of BACH2 as a sequence-specific DNA-binding transcription factor (class 1.1.1,
      basic leucine zipper factors / Jun-related). TFClass classification places BACH2
      as a DNA-binding TF expected to localize to chromatin when bound to DNA.
    action: ACCEPT
    reason: Correct. As a DNA-binding transcription factor, BACH2 localizes to chromatin
      where it binds MARE elements. ChIP-seq studies in lymphocytes have mapped BACH2
      binding across the genome. The ISA inference from TFClass classification is
      sound.
- term:
    id: GO:0000981
    label: DNA-binding transcription factor activity, RNA polymerase II-specific
  evidence_type: ISA
  original_reference_id: GO_REF:0000113
  review:
    summary: ISA annotation for DNA-binding transcription factor activity based on
      TFClass database classification (class 1.1.1). This duplicates the IBA annotation
      for the same term. TFClass independently confirms BACH2 as a bona fide DNA-binding
      transcription factor.
    action: ACCEPT
    reason: Correct and consistent with the IBA annotation. TFClass independently
      classifies BACH2 as a DNA-binding transcription factor (basic leucine zipper
      factor class). Duplicate annotations from independent evidence sources are acceptable.
references:
- id: GO_REF:0000002
  title: Gene Ontology annotation through association of InterPro records with GO
    terms
  findings: []
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings: []
- id: GO_REF:0000044
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location
    vocabulary mapping, accompanied by conservative changes to GO terms applied by
    UniProt
  findings: []
- id: GO_REF:0000052
  title: Gene Ontology annotation based on curation of immunofluorescence data
  findings: []
- id: GO_REF:0000107
  title: Automatic transfer of experimentally verified manual GO annotation data to
    orthologs using Ensembl Compara
  findings: []
- id: GO_REF:0000113
  title: Gene Ontology annotation of human sequence-specific DNA binding transcription
    factors (DbTFs) based on the TFClass database
  findings: []
- id: GO_REF:0000120
  title: Combined Automated Annotation using Multiple IEA Methods
  findings: []
- id: PMID:10949928
  title: Cloning and expression of human B cell-specific transcription factor BACH2
    mapped to chromosome 6q15
  findings:
  - statement: Original cloning of human BACH2 as a B cell-specific transcription
      factor belonging to the CNC-bZIP family.
    supporting_text: The transcription factor Bach2, a member of the BTB-basic region
      leucine zipper (bZip) factor family, binds to a 12-O-tetradecanoylphorbol-13-acetate
      (TPA)-responsive element and the related Maf-recognition element (MARE) by forming
      homodimers or heterodimers with Maf-related transcription factors.
- id: PMID:17018862
  title: Bcr-Abl signaling through the PI-3/S6 kinase pathway inhibits nuclear translocation
    of the transcription factor Bach2, which represses the antiapoptotic factor heme
    oxygenase-1
  findings:
  - statement: Demonstrated that BACH2 represses HMOX1 transcription. BCR-ABL/PI3K/S6K
      signaling phosphorylates BACH2 at Ser-521, promoting cytoplasmic accumulation
      and preventing nuclear translocation. S521A mutation leads to constitutive nuclear
      localization.
    supporting_text: We found that Bach2 is phosphorylated on S521 via the phosphatidylinositol-3/S6
      kinase pathway, and substitution of this site to alanine leads to nuclear accumulation
      of the protein, indicating that this phosphorylation is important for its subcellular
      localization.
- id: PMID:22194330
  title: The structure of the Bach2 POZ-domain dimer reveals an intersubunit disulfide
    bond
  findings:
  - statement: X-ray crystal structure of BACH2 BTB/POZ domain (residues 9-129) at
      2.1A resolution reveals a homodimer with an intersubunit disulfide bond at Cys-20
      that may regulate activity in oxidative stress responses.
    supporting_text: Here, the crystal structure of the human Bach2 POZ domain is
      reported at 2.1 Å resolution.
- id: PMID:23661758
  title: Networks of bZIP protein-protein interactions diversified over a billion
    years of evolution
  findings:
  - statement: Systematic measurement of bZIP dimerization specificities across seven
      species including human. Identified BACH2 heterodimeric interactions with small
      MAF proteins (MAFG, MAFF, MAFK) and BATF3.
    supporting_text: We studied the basic region-leucine zipper (bZIP) transcription
      factors and quantified bZIP dimerization networks for five metazoan and two
      single-cell species, measuring interactions in vitro for 2891 protein pairs.
- id: PMID:27052415
  title: 'The Bach Family of Transcription Factors: A Comprehensive Review.'
  findings:
  - statement: Comprehensive review of Bach1 and Bach2 transcription factors. Describes
      BACH2 as repressing target gene expression by forming heterodimers with small
      Maf proteins. Reviews roles in B cell class-switch recombination, T cell homeostasis,
      oxidative stress-mediated apoptosis, and innate/adaptive immune responses.
    supporting_text: The transcription factors Bach1 and Bach2, which belong to a
      basic region-leucine zipper (bZip) family, repress target gene expression by
      forming heterodimers with small Maf proteins.
- id: PMID:28112733
  title: Site-specific mapping of the human SUMO proteome reveals co-modification
    with phosphorylation
  findings:
  - statement: Identified BACH2 SUMOylation at Lys-382 and Lys-421 by mass spectrometry,
      suggesting SUMO-dependent regulation of BACH2 activity.
    supporting_text: Here we used an augmented K0-SUMO proteomics strategy to identify
      40,765 SUMO acceptor sites and quantify their fractional contribution for 6,747
      human proteins.
- id: PMID:28473536
  title: Impact of cytosine methylation on DNA binding specificities of human transcription
    factors
  findings:
  - statement: Systematic SELEX analysis of 542 human TFs including BACH2. Demonstrated
      sequence-specific double-stranded DNA binding by BACH2 and characterized binding
      specificities including effects of CpG methylation.
    supporting_text: By analysis of 542 human TFs with methylation-sensitive SELEX
      (systematic evolution of ligands by exponential enrichment), we found that there
      are also many TFs that prefer CpG-methylated sequences.
- id: PMID:28514442
  title: Architecture of the human interactome defines protein communities and disease
    networks
  findings:
  - statement: BioPlex 2.0 AP-MS study identifying BACH2 protein interactions including
      with FOSL2, BATF3, MAFF, and TULP3 among others.
    supporting_text: Here we present BioPlex 2.0 (Biophysical Interactions of ORFeome-derived
      complexes), which uses robust affinity purification-mass spectrometry methodology
      to elucidate protein interaction networks and co-complexes nucleated by more
      than 25% of protein-coding genes from the human genome
- id: PMID:28530713
  title: BACH2 immunodeficiency illustrates an association between super-enhancers
    and haploinsufficiency
  findings:
  - statement: Characterized human BACH2 haploinsufficiency (BRIDA/IMD60) caused by
      heterozygous variants L24P and E788K. Patients showed intestinal inflammation,
      recurrent infections, impaired lymphocyte maturation, and decreased immunoglobulin
      production. Demonstrated BACH2 is a key regulator of adaptive immunity and Treg/B
      cell function.
    supporting_text: Here we describe a syndrome of BACH2-related immunodeficiency
      and autoimmunity (BRIDA) that results from BACH2 haploinsufficiency. Affected
      subjects had lymphocyte-maturation defects that caused immunoglobulin deficiency
      and intestinal inflammation.
- id: PMID:32296183
  title: A reference map of the human binary protein interactome
  findings:
  - statement: HuRI reference interactome identifying binary protein interactions
      for BACH2 including canonical partners (MAFG, MAFK, MAFF) and many other proteins.
    supporting_text: Here we present a human 'all-by-all' reference interactome map
      of human binary protein interactions, or 'HuRI'. With approximately 53,000 protein-protein
      interactions, HuRI has approximately four times as many such interactions as
      there are high-quality curated interactions from small-scale studies.
- id: PMID:33961781
  title: Dual proteome-scale networks reveal cell-specific remodeling of the human
    interactome
  findings:
  - statement: BioPlex 3.0 interactome study confirming BACH2 interactions with small
      MAF proteins and other transcription factors.
    supporting_text: Here we present BioPlex 3.0, the most complete model of the human
      interactome to date, accompanied by a second interaction network acquired in
      HCT116 cells.
- id: PMID:40205054
  title: Multimodal cell maps as a foundation for structural and functional genomics
  findings:
  - statement: Multimodal cell mapping confirming BACH2-MAFK interaction.
    supporting_text: Here we construct a global map of human subcellular architecture
      through joint measurement of biophysical interactions and immunofluorescence
      images for over 5,100 proteins in U2OS osteosarcoma cells.
core_functions:
- molecular_function:
    id: GO:0001227
    label: DNA-binding transcription repressor activity, RNA polymerase II-specific
  description: BACH2 functions primarily as a sequence-specific DNA-binding transcriptional
    repressor. It heterodimerizes with small MAF proteins (MAFK, MAFG, MAFF) via its
    bZIP domain to bind MARE elements and repress target gene transcription. In B
    cells, it represses PRDM1/Blimp-1 to maintain germinal center identity. In T cells,
    it represses effector gene programs (Prdm1, Gata3, Irf4, Gzmb) to stabilize Treg
    identity and promote memory/stem-like CD8+ T cell states. It also represses HMOX1
    in the context of oxidative stress responses.
  directly_involved_in:
  - id: GO:0000122
    label: negative regulation of transcription by RNA polymerase II
  - id: GO:0030183
    label: B cell differentiation
  - id: GO:0090721
    label: primary adaptive immune response involving T cells and B cells
  locations:
  - id: GO:0005654
    label: nucleoplasm
  supported_by:
  - reference_id: PMID:17018862
    supporting_text: we showed that Bach2 transcriptionally represses heme oxygenase-1,
      an antiapoptotic factor up-regulated in CML
  - reference_id: PMID:28530713
    supporting_text: BACH2 acts as a repressive "guardian" TF that regulates the balance
      between a network of other TFs critical to T and B cell specification and maturation
- molecular_function:
    id: GO:0046982
    label: protein heterodimerization activity
  description: BACH2 heterodimerizes with small MAF proteins (MAFF, MAFG, MAFK) and
    other bZIP family members (BATF3, FOSL2) via its bZIP leucine zipper domain. Heterodimerization
    with small MAFs is essential for DNA binding and transcriptional repression at
    MARE elements. BACH2 also homodimerizes via its BTB/POZ domain (residues 37-103),
    forming a disulfide-linked dimer through Cys-20.
  locations:
  - id: GO:0005654
    label: nucleoplasm
  supported_by:
  - reference_id: PMID:23661758
    supporting_text: We studied the basic region-leucine zipper (bZIP) transcription
      factors and quantified bZIP dimerization networks for five metazoan and two
      single-cell species, measuring interactions in vitro for 2891 protein pairs
  - reference_id: PMID:22194330
    supporting_text: the crystal structure of the human Bach2 POZ domain is reported
      at 2.1 Å resolution

Gene Description

Existing Annotations Review

Core Functions

References

Deep Research

Falcon

Citations

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