id: Q3SYG4
gene_symbol: BBS9
product_type: PROTEIN
status: COMPLETE
taxon:
  id: NCBITaxon:9606
  label: Homo sapiens
description: >-
  BBS9 (PTHB1) is a core structural subunit of the BBSome, an octameric coat-like
  adaptor complex (BBS1, BBS2, BBS4, BBS5, BBS7, BBS8/TTC8, BBS9 and BBIP1/BBIP10)
  that sorts and traffics specific membrane and signaling-receptor cargo into and
  out of the primary cilium in conjunction with intraflagellar transport (IFT) and
  the small GTPase ARL6/BBS3. The N-terminal ~407 residues fold into a seven-bladed
  beta-propeller, followed by gamma-adaptin-ear (GAE), platform, hairpin and a
  C-terminal alpha-helical region; together with BBS2 and BBS7, BBS9 forms the
  central scaffold that organizes the complex. BBSome assembly is chaperonin-assisted
  (BBS6/BBS10/BBS12 with CCT/TRiC), and BBS9 stability is required for assembly. The
  protein localizes to nonmembranous centriolar satellites and the pericentriolar
  region in the cytoplasm and to the ciliary membrane, transition zone and tip. Its
  ciliary trafficking is regulated by partners including LZTFL1, ARL6/BBS3,
  AZI1/CEP131 and the NPHP5(IQCB1)/CEP290 module. Loss-of-function mutations
  (e.g. the destabilizing G141R variant) cause autosomal-recessive Bardet-Biedl
  syndrome, a ciliopathy featuring retinal degeneration, obesity, polydactyly,
  hypogenitalism, renal anomalies and cognitive impairment.
alternative_products:
- name: '1'
  id: Q3SYG4-1
- name: '2'
  id: Q3SYG4-2
  sequence_note: VSP_018426
- name: '3'
  id: Q3SYG4-3
  sequence_note: VSP_018428
- name: '4'
  id: Q3SYG4-4
  sequence_note: VSP_018427
- name: '5'
  id: Q3SYG4-5
  sequence_note: VSP_018421, VSP_018422, VSP_018423
- name: '6'
  id: Q3SYG4-6
  sequence_note: VSP_018424, VSP_018425
- name: '7'
  id: Q3SYG4-7
  sequence_note: VSP_054063
existing_annotations:
- term:
    id: GO:0016020
    label: membrane
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: is_active_in
  review:
    summary: >-
      Phylogenetic (IBA) "membrane" annotation. BBS9 is a peripheral component of
      the BBSome that associates with the ciliary membrane rather than being an
      integral membrane protein, and "membrane" is a very general parent term.
    action: MODIFY
    reason: >-
      The BBSome associates specifically with the ciliary membrane (GO:0060170),
      supported by direct evidence elsewhere in this record. Replace the generic
      parent "membrane" with the more informative ciliary membrane term; the
      is_active_in qualifier is also weak for a structural subunit.
    proposed_replacement_terms:
    - id: GO:0060170
      label: ciliary membrane
- term:
    id: GO:0034464
    label: BBSome
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: part_of
  review:
    summary: >-
      Phylogenetic (IBA) annotation placing BBS9 as part_of the BBSome. This is
      the defining, well-established cellular-component/complex membership for
      BBS9 and is independently supported by multiple IDA/IPI annotations in this
      record.
    action: ACCEPT
- term:
    id: GO:0060271
    label: cilium assembly
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: >-
      Phylogenetic (IBA) "cilium assembly" annotation. The BBSome is required for
      ciliogenesis, so this is a valid biological-process association, though it
      reflects a broad downstream phenotype rather than the precise mechanistic
      role (cargo trafficking into the cilium).
    action: KEEP_AS_NON_CORE
    reason: >-
      Supported by experimental work showing the BBSome is required for
      ciliogenesis (PMID:17574030). The more precise, mechanistic core BP is
      protein localization to cilium (GO:0061512); cilium assembly is retained as
      a valid but broader non-core process term.
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: >-
      IEA "cytoplasm" annotation derived from UniProt subcellular-location mapping.
      Consistent with the cytoplasmic (centriolar satellite / pericentriolar)
      pool of BBS9, but "cytoplasm" is a very general parent term.
    action: KEEP_AS_NON_CORE
    reason: >-
      Accurate but uninformative parent term superseded by the more specific
      cytoplasmic locations (centriolar satellite GO:0034451, pericentriolar
      material GO:0000242) annotated with direct evidence.
- term:
    id: GO:0005813
    label: centrosome
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: >-
      IEA "centrosome" annotation from UniProt subcellular-location mapping. BBS9
      localizes to the centrosome/MTOC region (pericentriolar material and
      centriolar satellites surround the centrosome).
    action: KEEP_AS_NON_CORE
    reason: >-
      Consistent with the pericentriolar/centriolar-satellite localization
      directly demonstrated for BBS9. A valid but broad location; the satellite
      and pericentriolar terms are more specific.
- term:
    id: GO:0034451
    label: centriolar satellite
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: >-
      IEA "centriolar satellite" annotation from UniProt subcellular-location
      mapping. The BBSome localizes to nonmembranous centriolar satellites in the
      cytoplasm; this is independently supported by direct evidence (PMID:23943788)
      and a PAN-GO/IBA call.
    action: ACCEPT
    reason: >-
      Well-supported localization; the BBSome is found at centriolar satellites
      (PMID:17574030; PMID:23943788). Redundant with the IDA annotation below but
      correct.
- term:
    id: GO:0034464
    label: BBSome
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: part_of
  review:
    summary: >-
      IEA (multiple-method) annotation placing BBS9 as part_of the BBSome.
      Redundant with, and confirmed by, the experimental IDA/IPI and IBA BBSome
      annotations.
    action: ACCEPT
    reason: >-
      Correct complex-membership call, the defining feature of BBS9.
- term:
    id: GO:0060170
    label: ciliary membrane
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: >-
      IEA "ciliary membrane" annotation from UniProt subcellular-location mapping.
      The BBSome associates with the ciliary membrane; independently supported by
      ComplexPortal IDA (PMID:19081074).
    action: ACCEPT
    reason: >-
      Correct and specific ciliary-membrane localization, well supported by
      experimental evidence.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:17574030
  qualifier: enables
  review:
    summary: >-
      IPI "protein binding" capturing BBSome intra-complex interactions of BBS9
      (with BBS1, BBS2/BBS9BXC9, BBS4, BBS5, TTC8) from the founding BBSome
      proteomics paper. "Protein binding" is uninformative per curation guidelines.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      The interactions are real and important, but the bare GO:0005515 term
      conveys no specific function. The informative content (BBSome subunit
      assembly) is already captured by the part_of GO:0034464 annotations.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:19081074
  qualifier: enables
  review:
    summary: >-
      IPI "protein binding" recording a BBSome intra-complex interaction (BBS4)
      from the BBIP10/BBSome study. Uninformative bare term per guidelines.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      Real BBSome interaction but GO:0005515 is non-informative; subunit
      membership is captured by part_of GO:0034464.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:20080638
  qualifier: enables
  review:
    summary: >-
      IPI "protein binding" recording BBS9 interactions during chaperonin-assisted
      BBSome assembly (with BBS12, BBS5, BBS1, BBS10, BBS4, BBS2). Uninformative
      bare term per guidelines.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      Interactions reflect BBSome assembly via the BBS6/10/12-CCT chaperonin
      module; GO:0005515 itself is non-informative. Captured by BBSome membership.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:22072986
  qualifier: enables
  review:
    summary: >-
      IPI "protein binding" recording the BBS9-LZTFL1 interaction (BBS9 region
      685-765 mediates LZTL1 binding), which regulates BBSome ciliary trafficking.
      Bare term is uninformative per guidelines.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      Biologically meaningful (LZTFL1 controls BBSome ciliary trafficking and
      Hedgehog/Smoothened), but GO:0005515 conveys no specific function. Could be
      better captured by a regulator-binding MF if needed; otherwise non-core.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:22139371
  qualifier: enables
  review:
    summary: >-
      IPI "protein binding" recording a BBS9-BBS2 interaction from the Bbs3
      knockout study. Bare term is uninformative per guidelines.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      Real BBSome intra-complex interaction but GO:0005515 is non-informative;
      captured by BBSome part_of.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:22500027
  qualifier: enables
  review:
    summary: >-
      IPI "protein binding" recording BBS9 interactions (BBS5, BBS1, BBS2) from
      the study of intrinsic and chaperonin-assisted sequential BBSome assembly.
      Bare term is uninformative per guidelines.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      Reflects ordered BBSome assembly interactions; GO:0005515 is non-informative.
      Captured by BBSome membership.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:25552655
  qualifier: enables
  review:
    summary: >-
      IPI "protein binding" recording a BBS9-IQCB1/NPHP5 interaction; NPHP5 and
      CEP290 regulate BBSome integrity and ciliary cargo delivery. Bare term is
      uninformative per guidelines.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      Biologically relevant regulatory interaction, but GO:0005515 conveys no
      specific function.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:27173435
  qualifier: enables
  review:
    summary: >-
      IPI "protein binding" from a high-throughput organelle proteomic landscape
      study (interactions with BBS5, BBS1, BBS4, BBS2, LZTFL1). Bare term is
      uninformative per guidelines.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      High-throughput interaction data; GO:0005515 is non-informative and the
      functional content is captured by BBSome membership.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:28514442
  qualifier: enables
  review:
    summary: >-
      IPI "protein binding" (with LZTFL1) from a large-scale interactome study.
      Bare term is uninformative per guidelines.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      High-throughput interactome data; GO:0005515 is non-informative.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:29039417
  qualifier: enables
  review:
    summary: >-
      IPI "protein binding" (with TTC8, BBS5, BBS1, BBS4, BBS2) from an
      amino-acid-resolution interaction-perturbation study. Bare term is
      uninformative per guidelines.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      BBSome intra-complex interactions; GO:0005515 is non-informative; captured
      by BBSome membership.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:33961781
  qualifier: enables
  review:
    summary: >-
      IPI "protein binding" (with BBS5, BBS1, LZTFL1) from the BioPlex
      proteome-scale interactome study. Bare term is uninformative per guidelines.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      High-throughput interactome data; GO:0005515 is non-informative.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:40205054
  qualifier: enables
  review:
    summary: >-
      IPI "protein binding" (with BBS1) from a multimodal cell-map / structural-
      genomics study. Bare term is uninformative per guidelines.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      High-throughput interaction data; GO:0005515 is non-informative.
- term:
    id: GO:0016020
    label: membrane
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: located_in
  review:
    summary: >-
      IEA "membrane" annotation transferred from the mouse ortholog via Ensembl
      Compara. Generic parent term; BBS9 associates with the ciliary membrane
      specifically.
    action: MODIFY
    reason: >-
      Redundant generic parent of ciliary membrane (GO:0060170), which is the
      informative location supported by direct evidence.
    proposed_replacement_terms:
    - id: GO:0060170
      label: ciliary membrane
- term:
    id: GO:0045444
    label: fat cell differentiation
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: involved_in
  review:
    summary: >-
      IEA "fat cell differentiation" transferred from the mouse ortholog via
      Ensembl Compara. Relates to the obesity phenotype of BBS but is an indirect,
      downstream physiological consequence rather than a direct molecular role of
      BBS9.
    action: KEEP_AS_NON_CORE
    reason: >-
      Plausible given BBS-associated obesity and adipocyte ciliary signaling, but
      indirect and non-core for a structural ciliary trafficking subunit.
- term:
    id: GO:0060271
    label: cilium assembly
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: involved_in
  review:
    summary: >-
      IEA "cilium assembly" transferred from the mouse ortholog via Ensembl
      Compara. Consistent with the BBSome's requirement for ciliogenesis; broad
      downstream process.
    action: KEEP_AS_NON_CORE
    reason: >-
      Valid but broader than the mechanistic core BP (protein localization to
      cilium); redundant with the IBA cilium assembly annotation.
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-5617815
  qualifier: located_in
  review:
    summary: >-
      TAS "cytosol" from a Reactome reaction (BBSome binds RAB3IP/Rabin8). Reflects
      the cytosolic pool of the BBSome before/around ciliary docking. General
      location term.
    action: KEEP_AS_NON_CORE
    reason: >-
      Correct but general parent location, superseded by the specific cytoplasmic
      and ciliary IDA terms; one of several redundant Reactome cytosol calls.
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-5624125
  qualifier: located_in
  review:
    summary: >-
      TAS "cytosol" from the Reactome "Formation of the BBSome" reaction. General
      location term reflecting cytosolic BBSome assembly.
    action: KEEP_AS_NON_CORE
    reason: >-
      Correct but general parent location; redundant with other cytosol/cytoplasm
      calls and superseded by specific IDA locations.
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-5624126
  qualifier: located_in
  review:
    summary: >-
      TAS "cytosol" from the Reactome "ARL6:GTP and the BBSome bind ciliary cargo"
      reaction. General location term.
    action: KEEP_AS_NON_CORE
    reason: >-
      Correct but general parent location; redundant Reactome cytosol call.
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-5624127
  qualifier: located_in
  review:
    summary: >-
      TAS "cytosol" from the Reactome "ARL6:GTP and the BBSome target cargo to the
      primary cilium" reaction. General location term.
    action: KEEP_AS_NON_CORE
    reason: >-
      Correct but general parent location; redundant Reactome cytosol call.
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-5624129
  qualifier: located_in
  review:
    summary: >-
      TAS "cytosol" from the Reactome "LZTFL1 binds the BBSome and prevents its
      traffic to the cilium" reaction. General location term.
    action: KEEP_AS_NON_CORE
    reason: >-
      Correct but general parent location; redundant Reactome cytosol call.
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: IDA
  original_reference_id: GO_REF:0000052
  qualifier: located_in
  review:
    summary: >-
      IDA "cytosol" from HPA immunofluorescence. Consistent with the cytoplasmic
      pool of BBS9; general location term.
    action: KEEP_AS_NON_CORE
    reason: >-
      Directly observed but a general location; the centriolar satellite and
      pericentriolar material terms are more informative for the cytoplasmic pool.
- term:
    id: GO:0005929
    label: cilium
  evidence_type: IDA
  original_reference_id: GO_REF:0000052
  qualifier: located_in
  review:
    summary: >-
      IDA "cilium" from HPA immunofluorescence. BBS9/the BBSome localizes to the
      primary cilium, a well-established and central localization.
    action: ACCEPT
    reason: >-
      Robustly supported ciliary localization, consistent with multiple
      independent IDA annotations.
- term:
    id: GO:0035869
    label: ciliary transition zone
  evidence_type: IDA
  original_reference_id: GO_REF:0000052
  qualifier: located_in
  review:
    summary: >-
      IDA "ciliary transition zone" from immunofluorescence. The BBSome passes
      through / is enriched at the transition zone, the ciliary gate where it
      sorts membrane cargo. Independently supported by PMID:23943788.
    action: ACCEPT
    reason: >-
      Directly observed and biologically coherent with BBSome cargo gating at the
      transition zone.
- term:
    id: GO:0097542
    label: ciliary tip
  evidence_type: IDA
  original_reference_id: GO_REF:0000052
  qualifier: located_in
  review:
    summary: >-
      IDA "ciliary tip" from HPA immunofluorescence. The BBSome moves along the
      axoneme with IFT trains and is detected at the ciliary tip, the IFT turnaround
      site.
    action: ACCEPT
    reason: >-
      Consistent with BBSome trafficking along the cilium with IFT; directly
      observed.
- term:
    id: GO:0034464
    label: BBSome
  evidence_type: IPI
  original_reference_id: PMID:19081074
  qualifier: part_of
  review:
    summary: >-
      IPI (ComplexPortal) annotation placing BBS9 as part_of the BBSome,
      from the BBIP10/BBSome characterization. Core complex membership.
    action: ACCEPT
    reason: >-
      Experimentally established BBSome subunit; the defining feature of BBS9.
- term:
    id: GO:0060170
    label: ciliary membrane
  evidence_type: IDA
  original_reference_id: PMID:19081074
  qualifier: located_in
  review:
    summary: >-
      IDA "ciliary membrane" (ComplexPortal). The BBSome associates with the
      ciliary membrane where it sorts membrane cargo; a defining, specific
      localization.
    action: ACCEPT
    reason: >-
      Directly supported ciliary-membrane localization, central to BBSome
      function.
- term:
    id: GO:0060271
    label: cilium assembly
  evidence_type: NAS
  original_reference_id: PMID:19081074
  qualifier: involved_in
  review:
    summary: >-
      NAS "cilium assembly" (ComplexPortal). The BBSome is required for
      ciliogenesis; this is a broad downstream process for BBS9.
    action: KEEP_AS_NON_CORE
    reason: >-
      Valid involvement but broader than the mechanistic core BP (protein
      localization to cilium); redundant with the IBA/IEA cilium assembly calls.
- term:
    id: GO:0061512
    label: protein localization to cilium
  evidence_type: IMP
  original_reference_id: PMID:23943788
  qualifier: involved_in
  review:
    summary: >-
      IMP "protein localization to cilium". This is the precise, mechanistic core
      biological process for BBS9: as a BBSome subunit it sorts/traffics specific
      membrane and signaling-receptor cargo into the primary cilium. BBSome
      disruption (e.g. via BBS9/BBS2/BBS7 destabilization) impairs ciliary cargo
      localization.
    action: ACCEPT
    reason: >-
      Experimentally supported (IMP) and represents the core function of BBS9 as a
      cargo-trafficking BBSome subunit; more mechanistic than the broader
      "cilium assembly" terms.
- term:
    id: GO:0005929
    label: cilium
  evidence_type: IDA
  original_reference_id: PMID:23943788
  qualifier: located_in
  review:
    summary: >-
      IDA "cilium" (GO_Central). Directly observed ciliary localization of BBS9;
      consistent with other IDA cilium annotations.
    action: ACCEPT
    reason: >-
      Well-supported core ciliary localization.
- term:
    id: GO:0034451
    label: centriolar satellite
  evidence_type: IDA
  original_reference_id: PMID:23943788
  qualifier: located_in
  review:
    summary: >-
      IDA "centriolar satellite" (GO_Central). Directly observed; the BBSome
      localizes to nonmembranous centriolar satellites in the cytoplasm
      (PMID:17574030).
    action: ACCEPT
    reason: >-
      Well-supported localization of the cytoplasmic BBSome pool.
- term:
    id: GO:0035869
    label: ciliary transition zone
  evidence_type: IDA
  original_reference_id: PMID:23943788
  qualifier: located_in
  review:
    summary: >-
      IDA "ciliary transition zone" (GO_Central). Directly observed; consistent
      with BBSome cargo gating at the ciliary gate. Independently supported by the
      HPA IDA call.
    action: ACCEPT
    reason: >-
      Reproducibly observed transition-zone localization.
- term:
    id: GO:0000242
    label: pericentriolar material
  evidence_type: IDA
  original_reference_id: PMID:22139371
  qualifier: located_in
  review:
    summary: >-
      IDA "pericentriolar material" (MGI). The BBSome localizes to the
      pericentriolar/centriolar-satellite region surrounding the basal body.
    action: ACCEPT
    reason: >-
      Directly observed; consistent with the centriolar-satellite/centrosome
      localization of the cytoplasmic BBSome pool.
- term:
    id: GO:0005929
    label: cilium
  evidence_type: IDA
  original_reference_id: PMID:22139371
  qualifier: located_in
  review:
    summary: >-
      IDA "cilium" (MGI). Directly observed ciliary localization of the BBSome.
    action: ACCEPT
    reason: >-
      Well-supported, redundant with other IDA cilium annotations.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:24550735
  qualifier: enables
  review:
    summary: >-
      IPI "protein binding" (with AZI1/CEP131, Q9UPN4), a centriolar satellite
      protein that regulates BBSome ciliary trafficking. Bare term is uninformative
      per guidelines.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      Biologically relevant regulatory interaction, but GO:0005515 conveys no
      specific function.
- term:
    id: GO:0005929
    label: cilium
  evidence_type: IDA
  original_reference_id: PMID:24550735
  qualifier: located_in
  review:
    summary: >-
      IDA "cilium" (UniProt). Directly observed ciliary localization of BBS9/the
      BBSome.
    action: ACCEPT
    reason: >-
      Well-supported, redundant ciliary localization.
- term:
    id: GO:0034464
    label: BBSome
  evidence_type: IDA
  original_reference_id: PMID:24550735
  qualifier: part_of
  review:
    summary: >-
      IDA (UniProt) annotation placing BBS9 as part_of the BBSome. Core complex
      membership.
    action: ACCEPT
    reason: >-
      Experimentally supported BBSome subunit; defining feature of BBS9.
- term:
    id: GO:0034464
    label: BBSome
  evidence_type: IDA
  original_reference_id: PMID:20080638
  qualifier: part_of
  review:
    summary: >-
      IDA (MGI) annotation placing BBS9 as part_of the BBSome, from the
      BBS6/10/12-CCT chaperonin BBSome-assembly study. Core complex membership.
    action: ACCEPT
    reason: >-
      Experimentally supported BBSome subunit.
- term:
    id: GO:0003674
    label: molecular_function
  evidence_type: ND
  original_reference_id: GO_REF:0000015
  qualifier: enables
  review:
    summary: >-
      ND (no biological data) root molecular_function placeholder. BBS9 has no
      known catalytic activity; it acts as a structural/scaffolding subunit of the
      BBSome. A "structural molecule activity" (GO:0005198) MF could in principle
      be proposed, but the scaffold role is well captured by the BBSome part_of
      cellular-component annotations.
    action: ACCEPT
    reason: >-
      Appropriate ND placeholder given the absence of a discrete catalytic MF;
      retained per GO conventions. See proposed_new_terms for an optional
      structural-molecule MF.
- term:
    id: GO:0045444
    label: fat cell differentiation
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  qualifier: involved_in
  review:
    summary: >-
      ISS "fat cell differentiation" transferred from the mouse ortholog. Relates
      to BBS-associated obesity; indirect downstream physiology, not a direct
      molecular role of BBS9.
    action: KEEP_AS_NON_CORE
    reason: >-
      Plausible given the BBS obesity phenotype, but indirect and non-core;
      duplicated by the IEA fat cell differentiation call.
- term:
    id: GO:0034464
    label: BBSome
  evidence_type: IDA
  original_reference_id: PMID:17574030
  qualifier: part_of
  review:
    summary: >-
      IDA (BHF-UCL) annotation placing BBS9 as part_of the BBSome, from the
      founding BBSome proteomics paper that defined the seven-subunit complex.
      Core complex membership.
    action: ACCEPT
    reason: >-
      The original experimental demonstration that BBS9 is a BBSome subunit; the
      defining feature of BBS9.
- term:
    id: GO:0005198
    label: structural molecule activity
  evidence_type: IDA
  original_reference_id: PMID:26085087
  qualifier: enables
  review:
    summary: >-
      Proposed NEW molecular-function annotation. BBS9 has no catalytic activity;
      its N-terminal seven-bladed beta-propeller plus GAE/platform/hairpin/
      C-terminal alpha-helical domains act as a structural scaffold that, with BBS2
      and BBS7, organizes the BBSome. The crystal structure (PDB 4YD8) and the
      destabilizing G141R disease variant support a structural role.
    action: NEW
    reason: >-
      Fills the molecular-function gap (currently only a root-level ND annotation)
      with a subunit-appropriate structural-molecule activity, consistent with the
      BBSome part_of cellular-component annotations.
references:
- id: GO_REF:0000015
  title: Use of the ND evidence code for Gene Ontology (GO) terms
  findings: []
- id: GO_REF:0000024
  title: Manual transfer of experimentally-verified manual GO annotation data to orthologs
    by curator judgment of sequence similarity
  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:0000120
  title: Combined Automated Annotation using Multiple IEA Methods
  findings: []
- id: PMID:26085087
  title: Structural characterization of Bardet-Biedl syndrome 9 protein (BBS9).
  findings: []
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: >-
      Cited by UniProt (PDB 4YD8) for the BBS9 N-terminal seven-bladed beta-propeller
      structure and for the destabilizing G141R disease variant. Supports the
      structural/scaffold role of BBS9. Abstract not cached; verified via the
      UniProt cross-reference and FT annotations.
- id: PMID:17574030
  title: A core complex of BBS proteins cooperates with the GTPase Rab8 to promote
    ciliary membrane biogenesis.
  findings: []
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: >-
      Founding BBSome paper; abstract verified. Defines the seven-subunit BBSome
      (including BBS9), its centriolar-satellite and ciliary-membrane localization,
      its requirement for ciliogenesis, and the Rab8/Rabin8 connection. Directly
      supports BBSome part_of and ciliary/centriolar-satellite localizations.
- id: PMID:19081074
  title: A BBSome subunit links ciliogenesis, microtubule stability, and acetylation.
  findings: []
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: >-
      Abstract verified. Characterizes BBIP10/BBIP1 as an eighth BBSome subunit and
      confirms BBSome membrane trafficking to/within the cilium; underpins the
      ComplexPortal BBSome membership and ciliary-membrane localization annotations.
- id: PMID:20080638
  title: BBS6, BBS10, and BBS12 form a complex with CCT/TRiC family chaperonins and
    mediate BBSome assembly.
  findings: []
- id: PMID:22072986
  title: A novel protein LZTFL1 regulates ciliary trafficking of the BBSome and Smoothened.
  findings: []
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: >-
      Cited by UniProt for the BBS9 685-765 LZTL1-interaction region and BBSome
      function. Establishes LZTFL1 as a regulator of BBSome ciliary trafficking and
      Hedgehog/Smoothened. Supports the BBS9-LZTFL1 interaction annotation.
- id: PMID:22139371
  title: Bardet-Biedl syndrome 3 (Bbs3) knockout mouse model reveals common BBS-associated
    phenotypes and Bbs3 unique phenotypes.
  findings: []
- id: PMID:22500027
  title: Intrinsic protein-protein interaction-mediated and chaperonin-assisted sequential
    assembly of stable bardet-biedl syndrome protein complex, the BBSome.
  findings: []
- id: PMID:23943788
  title: BBS mutations modify phenotypic expression of CEP290-related ciliopathies.
  findings: []
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: >-
      Full text available and read. Confirms BBS1/2/4/5/7/8/9 form the BBSome that
      sorts membrane proteins to cilia, and that loss of BBSome subunits affects
      ciliary cargo localization; supports the protein-localization-to-cilium IMP
      and the cilium / transition zone / centriolar satellite IDA annotations.
- id: PMID:24550735
  title: The centriolar satellite protein AZI1 interacts with BBS4 and regulates ciliary
    trafficking of the BBSome.
  findings: []
- id: PMID:25552655
  title: Nephrocystin proteins NPHP5 and Cep290 regulate BBSome integrity, ciliary
    trafficking and cargo delivery.
  findings: []
- id: PMID:27173435
  title: An organelle-specific protein landscape identifies novel diseases and molecular
    mechanisms.
  findings: []
- id: PMID:28514442
  title: Architecture of the human interactome defines protein communities and disease
    networks.
  findings: []
- id: PMID:29039417
  title: Protein interaction perturbation profiling at amino-acid resolution.
  findings: []
- id: PMID:33961781
  title: Dual proteome-scale networks reveal cell-specific remodeling of the human
    interactome.
  findings: []
- id: PMID:40205054
  title: Multimodal cell maps as a foundation for structural and functional genomics.
  findings: []
- id: Reactome:R-HSA-5617815
  title: BBSome binds RAB3IP
  findings: []
- id: Reactome:R-HSA-5624125
  title: Formation of the BBSome
  findings: []
- id: Reactome:R-HSA-5624126
  title: ARL6:GTP and the BBSome bind ciliary cargo
  findings: []
- id: Reactome:R-HSA-5624127
  title: ARL6:GTP and the BBSome target cargo to the primary cilium
  findings: []
- id: Reactome:R-HSA-5624129
  title: LZTFL1 binds the BBSome and prevents its traffic to the cilium
  findings: []
core_functions:
- description: >-
    As a core structural/scaffolding subunit of the BBSome (with BBS2 and BBS7),
    BBS9 contributes to the BBSome's cargo-sorting coat-adaptor activity, mediating
    trafficking of specific membrane and signaling-receptor cargo into and within
    the primary cilium (protein localization to cilium).
  supported_by:
  - reference_id: PMID:23943788
    supporting_text: >-
      Seven core BBS proteins (BBS1, BBS2, BBS4, BBS5, BBS7, BBS8 and BBS9) form a
      stable complex, called the BBSome, and this complex functions to sort
      membrane proteins to primary cilia
  - reference_id: PMID:17574030
    supporting_text: >-
      the BBSome is required for ciliogenesis but is dispensable for centriolar
      satellite function
  molecular_function:
    id: GO:0005198
    label: structural molecule activity
  directly_involved_in:
  - id: GO:0061512
    label: protein localization to cilium
  locations:
  - id: GO:0060170
    label: ciliary membrane
  - id: GO:0005929
    label: cilium
proposed_new_terms:
- proposed_name: structural constituent of the BBSome
  proposed_definition: >-
    The action of a molecule that contributes to the structural integrity and
    assembly of the BBSome, the octameric coat-like ciliary trafficking adaptor.
  justification: >-
    BBS9 currently has only a root-level ND molecular_function annotation. BBS9 has
    no catalytic activity; its function is to provide the beta-propeller / GAE /
    platform / alpha-helical scaffold that, with BBS2 and BBS7, organizes the
    BBSome. A specific structural-constituent MF (a child of structural molecule
    activity, GO:0005198) would better represent this scaffolding role than the
    generic parent and distinguish it from peripheral/regulatory interactions.
suggested_questions:
- question: >-
    Beyond serving as a structural scaffold, does the BBS9 beta-propeller or GAE
    domain directly recognize specific ciliary cargo or coat-adaptor partners, and
    can a discrete molecular function be assigned to any individual domain?
- question: >-
    Are any of the seven BBS9 splice isoforms (e.g. the truncated isoforms lacking
    the C-terminal half) assembly-competent or functionally distinct, or are they
    non-functional/unstable?
suggested_experiments:
- description: >-
    Cryo-EM or cross-linking mass spectrometry of reconstituted human BBSome with
    domain-resolved BBS9 deletions to map which BBS9 domains contact which subunits
    and which are required for cargo loading versus assembly.
- description: >-
    Rescue assays in BBS9-null ciliated cells comparing full-length BBS9 and each
    splice isoform / disease variant (e.g. G141R) for BBSome assembly, ciliary
    localization, and ciliary GPCR (e.g. SSTR3, MCHR1, Smoothened) trafficking.
- description: >-
    Proximity-labeling (BioID/TurboID) from BBS9 in ciliated cells to define the
    cargo and regulatory interactome at the basal body, transition zone and ciliary
    membrane.