id: P10734 gene_symbol: kni product_type: PROTEIN status: DRAFT taxon: id: NCBITaxon:7227 label: Drosophila melanogaster description: >- Knirps (Kni) is a Drosophila melanogaster zinc-finger transcription factor and a member of the nuclear receptor superfamily (subfamily NR0A). Unlike canonical nuclear receptors it consists essentially of a single N-terminal C4-type (two-zinc-finger) DNA-binding domain followed by a largely intrinsically disordered region, and it lacks a C-terminal ligand-binding domain; it therefore behaves as a ligand-independent ("orphan") sequence-specific factor rather than a hormone-activated receptor. Knirps acts in the nucleus as a short-range transcriptional repressor: bound to cis-regulatory elements it locally quenches nearby activators and blocks basal promoters over distances of about 100 bp, an activity it executes by recruiting the corepressors dCtBP (via a C-terminal PxDLS-type motif) and Groucho (via an eh1-like motif). As one of the zygotic gap genes it patterns the anterior-posterior axis of the embryonic trunk/abdomen by refining the expression boundaries of other gap genes and establishing pair-rule stripes such as even-skipped. Beyond early segmentation it is redeployed in later development: acting redundantly with its paralog Knirps-related (knrl) it directs tracheal cell migration and dorsal/ventral branch morphogenesis (in part by repressing spalt downstream of Dpp signaling), and it spatially restricts endoreduplication domains in the developing fore- and hindgut by repressing S-phase genes. existing_annotations: - term: id: GO:0005634 label: nucleus evidence_type: IBA original_reference_id: GO_REF:0000033 qualifier: is_active_in review: summary: Knirps is a nuclear transcription factor; nuclear localization is well supported. action: ACCEPT reason: Knirps is a sequence-specific nuclear repressor and UniProt curates its subcellular location as nucleus. This is a correct, core localization for the protein. supported_by: - reference_id: UniProtKB:P10734 supporting_text: 'SUBCELLULAR LOCATION: Nucleus' - term: id: GO:0004879 label: nuclear receptor activity evidence_type: IBA original_reference_id: GO_REF:0000033 qualifier: enables review: summary: Knirps belongs to the NR0 subfamily but is an orphan receptor that lost the ligand-binding domain and does not act as a ligand-activated receptor. action: MODIFY reason: "'Nuclear receptor activity' implies a ligand-activated transcription factor. Knirps is a member of nuclear-receptor subfamily NR0A, which retains the NR-type C4 zinc-finger DNA-binding domain but LACKS a ligand-binding domain (UniProt annotates only a DNA-binding/NR domain at 2..78 and disordered/low-complexity regions thereafter, with no LBD). It functions as a ligand-independent sequence-specific repressor, so the informative molecular function is DNA-binding transcription repressor activity rather than ligand-activated nuclear receptor activity. This IBA is phylogenetically reviewed but reflects the ancestral NR clade; MODIFY to the actual function." proposed_replacement_terms: - id: GO:0001227 label: DNA-binding transcription repressor activity, RNA polymerase II-specific propagation_review: root_cause: TERM_SCOPING_PROBLEM failure_modes: - FUNCTIONAL_DIVERGENCE - PSEUDO_OR_SUBACTIVITY_LOSS supported_by: - reference_id: UniProtKB:P10734 supporting_text: Belongs to the nuclear hormone receptor family. NR0 - reference_id: UniProtKB:P10734 supporting_text: 'FUNCTION: Transcriptional repressor.' - term: id: GO:0000785 label: chromatin evidence_type: IBA original_reference_id: GO_REF:0000033 qualifier: is_active_in review: summary: As a sequence-specific DNA-binding repressor Knirps acts on chromatin. action: ACCEPT reason: Knirps binds thousands of genomic cis-regulatory regions in vivo (ChIP), consistent with being active on chromatin. The IBA term is appropriate for a DNA-binding factor. supported_by: - reference_id: PMID:18271625 supporting_text: these sequence-specific DNA binding proteins bind with quantitatively different specificities to highly overlapping sets of several thousand genomic regions in blastoderm embryos - term: id: GO:0006357 label: regulation of transcription by RNA polymerase II evidence_type: IBA original_reference_id: GO_REF:0000033 qualifier: involved_in review: summary: Knirps regulates RNA Pol II transcription of developmental target genes. action: ACCEPT reason: Knirps regulates transcription of Pol II target genes (e.g. even-skipped, gap gene enhancers). This IBA term is correct and captures the process at an appropriate level. supported_by: - reference_id: PMID:19805071 supporting_text: Knirps has essential roles in patterning the Drosophila embryo by means of short-range repression, an activity that is essential for proper regulation of complex transcriptional control elements. - term: id: GO:0034056 label: estrogen response element binding evidence_type: IBA original_reference_id: GO_REF:0000033 qualifier: enables review: summary: Knirps binds its own gap-gene/knirps-response cis-regulatory elements, not estrogen response elements. action: MODIFY reason: This IBA is over-propagated from vertebrate steroid receptors. Knirps is a fly gap gene with a divergent NR-type DBD that binds knirps-response elements in target enhancers (e.g. the eve stripe 3 enhancer); there is no estrogen or estrogen receptor in this network and no evidence Knirps binds an estrogen response element. The essence (sequence-specific binding to transcription regulatory DNA) is sound, so MODIFY to the defensible Pol II cis-regulatory term, GO:0000978 - the same term the hairy review carries as an accepted existing annotation. proposed_replacement_terms: - id: GO:0000978 label: RNA polymerase II cis-regulatory region sequence-specific DNA binding propagation_review: root_cause: TERM_SCOPING_PROBLEM failure_modes: - WRONG_ORTHOLOG_OR_PARALOG - FUNCTIONAL_DIVERGENCE supported_by: - reference_id: UniProtKB:P10734 supporting_text: Binds to multiple sites in the eve - term: id: GO:0000122 label: negative regulation of transcription by RNA polymerase II evidence_type: IEA original_reference_id: GO_REF:0000108 qualifier: involved_in review: summary: Knirps is a transcriptional repressor of Pol II target genes. action: ACCEPT reason: Directly supported by experimental work showing Knirps is a short-range repressor of Pol II-transcribed targets such as even-skipped. Correct and core. supported_by: - reference_id: PMID:10982842 supporting_text: Two distinct repression functions were identified in Knirps. - term: id: GO:0003700 label: DNA-binding transcription factor activity evidence_type: IEA original_reference_id: GO_REF:0000002 qualifier: enables review: summary: Knirps is a sequence-specific DNA-binding transcription factor. action: ACCEPT reason: InterPro2GO mapping from the C4 zinc-finger nuclear-receptor DBD is correct. Knirps is a bona fide DNA-binding transcription factor (see also the IDA from ChIP). Broad but accurate. supported_by: - reference_id: PMID:18271625 supporting_text: Data were obtained using affinity-purified antibodies to KNI, KR, HB, GT, BCD, and CAD. - term: id: GO:0005634 label: nucleus evidence_type: IEA original_reference_id: GO_REF:0000044 qualifier: located_in review: summary: Nuclear localization from UniProt subcellular-location mapping. action: ACCEPT reason: Consistent with the IBA nucleus annotation and UniProt curation. Correct core localization (duplicate location by a different method is fine). supported_by: - reference_id: UniProtKB:P10734 supporting_text: 'SUBCELLULAR LOCATION: Nucleus' - term: id: GO:0006355 label: regulation of DNA-templated transcription evidence_type: IEA original_reference_id: GO_REF:0000120 qualifier: involved_in review: summary: Knirps regulates DNA-templated transcription. action: ACCEPT reason: Correct but general parent of the more specific negative-regulation terms. Accept as a broad IEA that is not wrong. supported_by: - reference_id: PMID:19805071 supporting_text: Knirps has essential roles in patterning the Drosophila embryo by means of short-range repression - term: id: GO:0008270 label: zinc ion binding evidence_type: IEA original_reference_id: GO_REF:0000002 qualifier: enables review: summary: The C4-type zinc fingers of the DNA-binding domain coordinate zinc. action: ACCEPT reason: UniProt annotates two NR C4-type zinc fingers (ZN_FING 5..25 and 42..66) within the DNA-binding domain; zinc-ion binding is a correct, structurally supported molecular function. supported_by: - reference_id: UniProtKB:P10734 supporting_text: NR C4-type - term: id: GO:0030522 label: intracellular receptor signaling pathway evidence_type: IEA original_reference_id: GO_REF:0000108 qualifier: involved_in review: summary: Knirps is an orphan NR that lost the ligand-binding domain and does not transduce a receptor signal. action: REMOVE reason: This is an automated inter-ontology inference (GO_REF:0000108) whose WITH/FROM is GO:0004879, i.e. it hangs off the nuclear receptor activity IBA that this review is separately modifying, so it inherits that annotation's error. Knirps lacks a ligand-binding domain and has no known ligand; it acts as a constitutive, ligand-independent sequence-specific transcriptional repressor, not as a signal-transducing intracellular receptor. The mapping is biologically inapplicable to this orphan factor and should be removed. supported_by: - reference_id: UniProtKB:P10734 supporting_text: Belongs to the nuclear hormone receptor family. NR0 - term: id: GO:0043565 label: sequence-specific DNA binding evidence_type: IEA original_reference_id: GO_REF:0000002 qualifier: enables review: summary: Knirps binds specific DNA sequences in target enhancers. action: ACCEPT reason: Correct and core. Knirps binds specific recognition sequences in cis-regulatory modules (e.g. eve enhancers) via its C4 zinc-finger DBD, as shown by footprinting and in vivo ChIP. supported_by: - reference_id: UniProtKB:P10734 supporting_text: Binds to multiple sites in the eve - term: id: GO:0048731 label: system development evidence_type: IEA original_reference_id: GO_REF:0000117 qualifier: involved_in review: summary: Very general developmental term generated by ARBA. action: KEEP_AS_NON_CORE reason: Knirps is a developmental protein, so the term is not wrong, but "system development" is far too general to be informative and does not represent a core function. Retain as non-core. supported_by: - reference_id: PMID:9811580 supporting_text: possess multiple and redundant functions during tracheal development - term: id: GO:0160108 label: animal gross anatomical part developmental process evidence_type: IEA original_reference_id: GO_REF:0000117 qualifier: involved_in review: summary: Very general developmental term generated by ARBA. action: KEEP_AS_NON_CORE reason: Not wrong (Knirps contributes to development of anatomical structures such as the trachea and gut) but far too general to be a core function. Retain as non-core. supported_by: - reference_id: PMID:11118880 supporting_text: crucial for gut morphogenesis - term: id: GO:0005515 label: protein binding evidence_type: IPI original_reference_id: PMID:14605208 qualifier: enables review: summary: Bare "protein binding" from a genome-wide two-hybrid proteome map; the curated partner is dCtBP. action: MODIFY reason: "'protein binding' is uninformative, but the partner is not unknown: the GOA row carries WITH/FROM = UniProtKB:O46036, resolved by the fetched UniProt record as dCtBP (kni-uniprot.txt:97, 'P10734; O46036: CtBP'). Partner identity here is curated input data rather than something that has to be recovered from the abstract, so the informative molecular function can be assigned: transcription corepressor binding, matching the other dCtBP rows on this record." proposed_replacement_terms: - id: GO:0001222 label: transcription corepressor binding supported_by: - reference_id: PMID:14605208 supporting_text: we present a two-hybrid-based protein-interaction map of the fly proteome - term: id: GO:0005515 label: protein binding evidence_type: IPI original_reference_id: PMID:17972097 qualifier: enables review: summary: dCtBP corepressor paper; the curated partner for this IPI is dCtBP. action: MODIFY reason: "'protein binding' is uninformative. The cached record is abstract-only, but the partner does not depend on the abstract: the GOA row carries WITH/FROM = UniProtKB:O46036, resolved by the fetched UniProt record as dCtBP (kni-uniprot.txt:97, 'P10734; O46036: CtBP'). The paper is about dCtBP and the PXDLS-motif DNA-binding repressors it partners with, and Knirps carries such a motif, so the assay context is consistent with the curated partner. Assign the informative molecular function, transcription corepressor binding, rather than deferring: the unverifiable-evidence policy applies to claims that must be recovered from an abstract, not to partner identity supplied in the input files." proposed_replacement_terms: - id: GO:0001222 label: transcription corepressor binding supported_by: - reference_id: PMID:17972097 supporting_text: Drosophila CtBP (dCtBP) functions as a transcriptional corepressor for deoxyribonucleic acid (DNA)-binding repressors containing the short amino acid motif, PXDLS - term: id: GO:0005515 label: protein binding evidence_type: IPI original_reference_id: PMID:19805071 qualifier: enables review: summary: This IPI documents the Knirps-Groucho interaction; Groucho is a corepressor. action: MODIFY reason: "'protein binding' is uninformative. This paper shows Knirps physically interacts with the Groucho corepressor as part of its short-range repression complex, via an eh1-like motif. The informative molecular function is transcription corepressor binding." proposed_replacement_terms: - id: GO:0001222 label: transcription corepressor binding supported_by: - reference_id: PMID:19805071 supporting_text: we report that Groucho is a functional part of the Knirps short-range repression complex. - reference_id: PMID:19805071 supporting_text: The corepressor interaction is mediated via an eh-1 like motif present in the N terminus and a conserved region present in the central portion of Knirps. - term: id: GO:0005515 label: protein binding evidence_type: IPI original_reference_id: PMID:30995488 qualifier: enables review: summary: Interaction detected in a genome-wide yeast two-hybrid interactome; the curated partner is dCtBP, a corepressor. action: MODIFY reason: "'protein binding' is uninformative. The partner does not have to be inferred from the screen's scope: the GOA row carries WITH/FROM = UniProtKB:O46036, which the fetched UniProt record resolves as dCtBP (kni-uniprot.txt:97, 'P10734; O46036: CtBP'). dCtBP is a transcriptional corepressor, not a sequence-specific DNA-binding transcription factor. The paper's own remark that a broader screen including non-DNA-binding cofactors might reveal further co-regulatory interactions shows why the screen's nominal TF-only scope was never a safe basis for inferring a partner's class - dCtBP is recorded as a partner detected here regardless. The appropriate specific molecular function is therefore transcription corepressor binding, consistent with the PMID:10982842 and PMID:19805071 rows for the same partner." proposed_replacement_terms: - id: GO:0001222 label: transcription corepressor binding supported_by: - reference_id: PMID:30995488 supporting_text: we identified 1,983 protein-protein interactions (PPIs) - reference_id: PMID:30995488 supporting_text: a broader PPI screen including non-DNA-binding cofactors and chromatin-associated proteins may reveal additional co-regulatory interactions - term: id: GO:0045892 label: negative regulation of DNA-templated transcription evidence_type: IDA original_reference_id: PMID:9811580 qualifier: involved_in review: summary: Knirps directly represses spalt transcription during tracheal development. action: ACCEPT reason: Direct experimental demonstration that Knirps represses transcription of its target spalt, via direct binding to a spalt cis-regulatory element. Supports the repressor molecular function and its deployment; correct. supported_by: - reference_id: PMID:9811580 supporting_text: In dorsal tracheal cells knirps/knirps related activity represses the transcription factor SPALT - reference_id: PMID:9811580 supporting_text: the border between cells acquiring dorsal branch and dorsal trunk identity is established by the direct interaction of KNIRPS with a spalt cis-regulatory element - term: id: GO:0006355 label: regulation of DNA-templated transcription evidence_type: IMP original_reference_id: PMID:19805071 qualifier: involved_in review: summary: Mutational analysis shows Knirps regulates transcription (of even-skipped) via its corepressor interactions. action: ACCEPT reason: Supported by mutational/structure-function experiments in transgenic embryos demonstrating Knirps regulation of even-skipped. Broad but correct; the more specific negative-regulation term is also annotated. supported_by: - reference_id: PMID:19805071 supporting_text: is required for regulation of even-skipped - term: id: GO:0006355 label: regulation of DNA-templated transcription evidence_type: IGI original_reference_id: PMID:19805071 qualifier: involved_in review: summary: Genetic interaction (Knirps with Groucho) supporting its role in transcriptional regulation. action: ACCEPT reason: The genetic/functional interaction between Knirps and the Groucho corepressor supports Knirps' role in regulating transcription of target genes such as even-skipped. Correct (duplicate GO id by a different evidence code is fine). supported_by: - reference_id: PMID:19805071 supporting_text: this interaction is important for the CtBP-independent repression activity of Knirps and is required for regulation of even-skipped - term: id: GO:0045892 label: negative regulation of DNA-templated transcription evidence_type: IDA original_reference_id: PMID:19805071 qualifier: involved_in review: summary: Knirps is a direct short-range transcriptional repressor. action: ACCEPT reason: Directly demonstrated repression activity of Knirps on reporter and endogenous targets (even-skipped). This is a core biological process for the gene. supported_by: - reference_id: PMID:19805071 supporting_text: Groucho is a functional part of the Knirps short-range repression complex - term: id: GO:0001227 label: DNA-binding transcription repressor activity, RNA polymerase II-specific evidence_type: IDA original_reference_id: PMID:10982842 qualifier: enables review: summary: The central, experimentally demonstrated molecular function of Knirps. action: ACCEPT reason: Structure-function analysis in transgenic embryos identified two distinct repression activities in Knirps acting on Pol II target enhancers, establishing it as a DNA-binding transcriptional repressor. This is the core molecular function of the gene. supported_by: - reference_id: PMID:10982842 supporting_text: Two distinct repression functions were identified in Knirps. - reference_id: PMID:10982842 supporting_text: Repressors such as Knirps, Krüppel, and Snail mediate short-range repression and interact with the dCtBP corepressor. - term: id: GO:0140297 label: DNA-binding transcription factor binding evidence_type: IPI original_reference_id: PMID:10982842 qualifier: enables review: summary: This IPI captures the Knirps-dCtBP interaction; dCtBP is a corepressor, so a corepressor-binding term is more precise. action: MODIFY reason: The paper maps a dCtBP-binding motif in the Knirps C-terminus and shows dCtBP-dependent repression. dCtBP is a transcriptional corepressor (not a DNA-binding transcription factor), so the more accurate molecular function is transcription corepressor binding rather than DNA-binding transcription factor binding. proposed_replacement_terms: - id: GO:0001222 label: transcription corepressor binding supported_by: - reference_id: PMID:10982842 supporting_text: One repression activity depends on dCtBP binding, and this function maps to a C-terminal region of Knirps that contains a dCtBP binding motif. - term: id: GO:0003700 label: DNA-binding transcription factor activity evidence_type: IDA original_reference_id: PMID:18271625 qualifier: enables review: summary: In vivo ChIP with anti-KNI antibodies demonstrates sequence-specific genome binding. action: ACCEPT reason: Genome-wide chromatin immunoprecipitation using affinity-purified Knirps antibodies shows Knirps binds thousands of genomic regions with sequence specificity in blastoderm embryos, directly demonstrating DNA-binding transcription factor activity. supported_by: - reference_id: PMID:18271625 supporting_text: Data were obtained using affinity-purified antibodies to KNI, KR, HB, GT, BCD, and CAD. - reference_id: PMID:18271625 supporting_text: these sequence-specific DNA binding proteins bind with quantitatively different specificities to highly overlapping sets of several thousand genomic regions in blastoderm embryos - term: id: GO:0007088 label: regulation of mitotic nuclear division evidence_type: IMP original_reference_id: PMID:11118880 qualifier: involved_in review: summary: The cited paper is about endoreduplication (endocycles) in the gut, not mitotic nuclear division. action: MODIFY reason: Fuss et al. show that knirps/knirps-related spatially restrict endoreduplication (endocycle) domains in the fore- and hindgut by transcriptionally repressing S-phase genes. The process assayed is endoreduplication, not mitotic nuclear division, so "regulation of mitotic nuclear division" is the wrong cell-cycle process. MODIFY to regulation of DNA endoreduplication. This is a non-core, tissue-specific developmental role. proposed_replacement_terms: - id: GO:0032875 label: regulation of DNA endoreduplication supported_by: - reference_id: PMID:11118880 supporting_text: the Drosophila knirps and knirps-related genes are key components to spatially restrict endoreduplication domains - reference_id: PMID:11118880 supporting_text: transcriptionally repress S-phase genes of the cell cycle required for DNA replication - term: id: GO:0007354 label: zygotic determination of anterior/posterior axis, embryo evidence_type: TAS original_reference_id: PMID:15382142 qualifier: involved_in review: summary: Knirps is a zygotic gap gene patterning the embryonic A-P axis. action: ACCEPT reason: Knirps is one of the four zygotic gap genes that, downstream of the maternal Bicoid/Caudal gradients, segment the anterior-posterior axis of the embryonic trunk. This is a canonical, core embryonic role. The TAS review supports the gap-gene control of segmentation; the explicit gap-gene identity of kni is documented directly in PMID:18271625. supported_by: - reference_id: PMID:18271625 supporting_text: These six genes encode transcription factors that work together to segment the A-P axis of the embryonic trunk - reference_id: PMID:15382142 supporting_text: their striped expression gradually coming under the control of gap genes - term: id: GO:0007427 label: epithelial cell migration, open tracheal system evidence_type: TAS original_reference_id: PMID:10943305 qualifier: involved_in review: summary: Knirps (with knrl) controls tracheal cell migration and branch morphogenesis. action: KEEP_AS_NON_CORE reason: Knirps and Knirps-related redundantly control tracheal cell migration and branching, mediating Dpp signaling and repressing spalt. This is a well-documented but secondary (non-core) developmental deployment of the same repressor activity. The original TAS reference (PMID:10943305) is a review with no accessible abstract in the cache; the underlying biology is established experimentally in PMID:9811580, cited here. supported_by: - reference_id: PMID:9811580 supporting_text: knirps/knirps related activity is necessary to mediate DPP signaling which is required for tracheal cell migration and formation of the dorsal and ventral branches - term: id: GO:0035290 label: trunk segmentation evidence_type: TAS original_reference_id: PMID:15382142 qualifier: involved_in review: summary: Knirps is a trunk/abdominal gap gene essential for segmentation. action: ACCEPT reason: Trunk (abdominal) segmentation is the canonical, core biological role of the knirps gap gene, established since its discovery as a gap gene required for abdominal segmentation. The TAS review supports gap-gene control of segment patterning, and kni's gap-gene identity in trunk A-P patterning is documented directly in PMID:18271625. supported_by: - reference_id: PMID:18271625 supporting_text: These six genes encode transcription factors that work together to segment the A-P axis of the embryonic trunk - reference_id: UniProtKB:P10734 supporting_text: Plays an essential role in the segmentation process core_functions: - description: Short-range, sequence-specific DNA-binding transcriptional repressor (RNA Pol II-specific) that patterns the embryonic trunk as a gap gene by locally quenching activators and blocking basal promoters at target enhancers such as the even-skipped stripe enhancers. molecular_function: id: GO:0001227 label: DNA-binding transcription repressor activity, RNA polymerase II-specific directly_involved_in: - id: GO:0035290 label: trunk segmentation - id: GO:0007354 label: zygotic determination of anterior/posterior axis, embryo - id: GO:0045892 label: negative regulation of DNA-templated transcription locations: - id: GO:0005634 label: nucleus supported_by: - reference_id: PMID:10982842 supporting_text: Two distinct repression functions were identified in Knirps. - reference_id: PMID:19805071 supporting_text: Knirps has essential roles in patterning the Drosophila embryo by means of short-range repression, an activity that is essential for proper regulation of complex transcriptional control elements. - description: Sequence-specific DNA binding to target cis-regulatory elements via an N-terminal C4-type (two zinc-finger) nuclear-receptor DNA-binding domain that coordinates zinc; demonstrated in vivo by genome-wide chromatin immunoprecipitation. molecular_function: id: GO:0043565 label: sequence-specific DNA binding locations: - id: GO:0005634 label: nucleus supported_by: - reference_id: UniProtKB:P10734 supporting_text: NR C4-type - reference_id: PMID:18271625 supporting_text: these sequence-specific DNA binding proteins bind with quantitatively different specificities to highly overlapping sets of several thousand genomic regions in blastoderm embryos - description: Recruitment of transcriptional corepressors (dCtBP via a C-terminal PxDLS-type motif and Groucho via an eh1-like motif) to execute short-range repression. molecular_function: id: GO:0001222 label: transcription corepressor binding supported_by: - reference_id: PMID:10982842 supporting_text: One repression activity depends on dCtBP binding, and this function maps to a C-terminal region of Knirps that contains a dCtBP binding motif. - reference_id: PMID:19805071 supporting_text: we report that Groucho is a functional part of the Knirps short-range repression complex. 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:0000108 title: Automatic assignment of GO terms using logical inference, based on on inter-ontology links findings: [] - id: GO_REF:0000117 title: Electronic Gene Ontology annotations created by ARBA machine learning models findings: [] - id: GO_REF:0000120 title: Combined Automated Annotation using Multiple IEA Methods findings: [] - id: UniProtKB:P10734 title: 'UniProtKB P10734 (KNIR_DROME): Zygotic gap protein knirps' findings: - statement: Knirps is a transcriptional repressor that binds multiple sites in the eve stripe 3 enhancer and is essential for segmentation by refining gap-gene patterns and establishing pair-rule stripes. supporting_text: 'FUNCTION: Transcriptional repressor. Binds to multiple sites in the eve' - statement: Knirps has an N-terminal nuclear-receptor C4-type DNA-binding domain with two zinc fingers and belongs to the NR0 subfamily (which lacks a ligand-binding domain). supporting_text: Belongs to the nuclear hormone receptor family. NR0 reference_review: relevance: HIGH correctness: VERIFIED review_notes: UniProt record for P10734; confirms repressor function, nuclear localization, the NR-type C4 zinc-finger DBD, NR0 (LBD-less orphan) subfamily membership, and dCtBP/gro interactions. Used to justify the nucleus, zinc-binding, DNA-binding, and NR-activity MODIFY calls. - id: PMID:10943305 title: 'Cell-cell interaction during Drosophila embryogenesis: novel mechanisms and molecules.' findings: [] reference_review: relevance: LOW correctness: UNVERIFIED review_notes: Review; cited as the TAS source for the tracheal epithelial cell migration annotation, but no abstract text is available in the cache so the specific claim could not be verified against it. The underlying biology is supported by PMID:9811580. - id: PMID:10982842 title: dCtBP-dependent and -independent repression activities of the Drosophila Knirps protein. findings: - statement: Knirps has two separable repression activities, one dependent on dCtBP binding (C-terminal dCtBP-binding motif) and one dCtBP-independent (N-terminal region). supporting_text: One repression activity depends on dCtBP binding, and this function maps to a C-terminal region of Knirps that contains a dCtBP binding motif. reference_review: relevance: HIGH correctness: VERIFIED review_notes: Primary structure-function study of Knirps repression; abstract available in cache. Directly supports the repressor MF (GO:0001227) and the dCtBP corepressor binding. - id: PMID:11118880 title: Control of endoreduplication domains in the Drosophila gut by the knirps and knirps-related genes. findings: - statement: knirps and knirps-related spatially restrict endoreduplication domains in the gut by transcriptionally repressing S-phase genes. supporting_text: transcriptionally repress S-phase genes of the cell cycle required for DNA replication reference_review: relevance: HIGH correctness: VERIFIED review_notes: Primary paper on the gut endoreduplication role; abstract available. Shows the process is endoreduplication (endocycle), supporting the MODIFY of GO:0007088 to GO:0032875. - id: PMID:14605208 title: A protein interaction map of Drosophila melanogaster. findings: [] reference_review: relevance: LOW correctness: VERIFIED review_notes: Genome-wide two-hybrid proteome map; abstract available. The cached record does not name the specific Knirps partner, but the GOA row supplies it as WITH/FROM = UniProtKB:O46036, resolved by the fetched UniProt record as dCtBP (kni-uniprot.txt:97), so the bare protein-binding annotation is a MODIFY to GO:0001222 rather than an uninformative non-core keep. - id: PMID:15382142 title: The evolution of arthropod segmentation mechanisms. findings: [] reference_review: relevance: MEDIUM correctness: VERIFIED review_notes: Review of arthropod segmentation used as the TAS source for the trunk segmentation and A-P axis annotations. Supports gap-gene control of segmentation at a general level; kni's explicit gap-gene identity is documented in PMID:18271625. - id: PMID:17972097 title: Structurally related Arabidopsis ANGUSTIFOLIA is functionally distinct from the transcriptional corepressor CtBP. findings: [] reference_review: relevance: LOW correctness: UNVERIFIED review_notes: Arabidopsis ANGUSTIFOLIA vs dCtBP; abstract-only cache, hence UNVERIFIED as a statement about the cached text, since a direct Knirps interaction is not recoverable from the abstract. Partner identity does not depend on it, because the GOA row carries WITH/FROM = UniProtKB:O46036, resolved by the fetched UniProt record as dCtBP (kni-uniprot.txt:97), so the annotation is a MODIFY to GO:0001222 rather than UNDECIDED. - id: PMID:18271625 title: Transcription factors bind thousands of active and inactive regions in the Drosophila blastoderm. findings: - statement: Knirps (kni) is one of the six maternal/gap factors; ChIP with anti-KNI antibodies shows it binds several thousand genomic regions with sequence specificity in the blastoderm. supporting_text: these sequence-specific DNA binding proteins bind with quantitatively different specificities to highly overlapping sets of several thousand genomic regions in blastoderm embryos reference_review: relevance: HIGH correctness: VERIFIED review_notes: Full text available; explicitly names kni as a gap gene and reports in vivo Knirps ChIP. Supports the IDA DNA-binding TF activity and the trunk/A-P segmentation role. - id: PMID:19805071 title: Groucho corepressor functions as a cofactor for the Knirps short-range transcriptional repressor. findings: - statement: Groucho is a functional part of the Knirps short-range repression complex, recruited via an eh1-like N-terminal motif, and mediates CtBP-independent repression of even-skipped. supporting_text: we report that Groucho is a functional part of the Knirps short-range repression complex. reference_review: relevance: HIGH correctness: VERIFIED review_notes: Full text available; directly supports Groucho (corepressor) binding, the short-range repression mechanism, and regulation of even-skipped. - id: PMID:30995488 title: A Comprehensive Drosophila melanogaster Transcription Factor Interactome. findings: - statement: Genome-wide yeast two-hybrid interactome among Drosophila sequence-specific transcription factors, reporting 1,983 protein-protein interactions. supporting_text: we identified 1,983 protein-protein interactions (PPIs) reference_review: relevance: MEDIUM correctness: VERIFIED review_notes: TF-TF interactome; full text available. Cited for a Knirps protein-binding IPI whose partner is supplied by the GOA row as WITH/FROM = UniProtKB:O46036, resolved by the fetched UniProt record as dCtBP (kni-uniprot.txt:97) - a corepressor, hence the MODIFY to GO:0001222. The screen's nominal restriction to sequence-specific TFs is not a safe basis for inferring the partner class, since dCtBP is itself recorded as a partner detected here; the curated WITH/FROM accession is what carries the call. - id: PMID:9811580 title: The transcription factors KNIRPS and KNIRPS RELATED control cell migration and branch morphogenesis during Drosophila tracheal development. findings: - statement: knirps/knirps-related redundantly control tracheal cell migration and dorsal/ventral branch formation, mediating Dpp signaling and repressing spalt. supporting_text: knirps/knirps related activity is necessary to mediate DPP signaling which is required for tracheal cell migration and formation of the dorsal and ventral branches reference_review: relevance: HIGH correctness: VERIFIED review_notes: Primary tracheal-development paper; abstract available. Supports the tracheal cell migration/branching role and direct repression of spalt. suggested_questions: - question: What are the direct, physiological genome-wide target genes of Knirps in the abdominal segmentation network versus in the trachea and gut, and how much target selection is shared with its paralog knrl? - question: Does Knirps have any endogenous small-molecule ligand or regulatory metabolite despite lacking a canonical ligand-binding domain, or is it strictly a constitutive orphan factor? suggested_experiments: - description: ChIP-seq plus tissue-specific RNA-seq of knirps loss- and gain-of-function in blastoderm, tracheal primordia, and gut to define direct targets and separate core (segmentation) from redeployed (tracheal/gut) regulatory programs. - description: Structure-guided separation-of-function mutants of the dCtBP (PxDLS) and Groucho (eh1-like) motifs to quantify the contribution of each corepressor to repression at distinct enhancers in vivo.