BBS10 is a vertebrate-specific, chaperonin-like protein of the group II (TCP-1/CCT/TRiC) chaperonin family. Together with the related chaperonin-like BBS proteins MKKS (BBS6) and BBS12, the CCT/TRiC chaperonin, and BBS7, it forms the cytoplasmic BBS-chaperonin complex that mediates assembly of the BBSome, the octameric ciliary trafficking complex. BBS10 functions as an assembly factor (chaperone) rather than as a stable structural subunit of the mature BBSome: it binds BBS subunits (BBS7, BBS9, BBS12) and promotes their association with CCT chaperonins to drive ordered assembly of the BBSome core (BBS7-BBS2-BBS9). It retains the conserved Cpn60/TCP-1 nucleotide-binding domain and is predicted to bind ATP, though direct chaperonin/ATPase folding activity has not been demonstrated biochemically. Loss-of-function mutations in BBS10 impair BBSome assembly and are a major cause of Bardet-Biedl syndrome (BBS10), an autosomal recessive ciliopathy characterized by retinal degeneration, obesity, polydactyly, renal abnormalities, hypogenitalism and cognitive impairment.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0051131 chaperone-mediated protein complex assembly | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic (IBA) propagation of the core, defining function of BBS10: acting as a chaperonin-like factor that mediates assembly of the BBSome protein complex. This is well supported by direct experimental evidence in human/mouse/zebrafish systems and is consistent with the IMP annotation to the same term. Reason: BBS10 is one of the three chaperonin-like BBS proteins that, with CCT/TRiC, mediate BBSome assembly [PMID:20080638; PMID:22500027]. This BP term accurately captures its core role and the IBA evidence aligns with experimental data. The falcon deep-research synthesis reinforces that BBS10 acts as an assembly factor rather than a structural BBSome subunit. Supporting Evidence: file:human/BBS10/BBS10-deep-research-falcon.md BBS10 is not itself a component of the mature BBSome file:human/BBS10/BBS10-deep-research-falcon.md BBS10 functions as part of a specialized **BBS/CCT assembly machinery** required for BBSome biogenesis |
| GO:0005524 ATP binding | IEA GO_REF:0000002 | ACCEPT | Summary: Electronic annotation of ATP binding from the conserved Cpn60/TCP-1 chaperonin (InterPro IPR002423; Pfam PF00118) nucleotide-binding domain. BBS10 belongs to the TCP-1 chaperonin family and retains the equatorial nucleotide-binding domain, so ATP binding is plausible and is the molecular basis presumed for its chaperone activity. Reason: Domain-based ATP-binding annotation is consistent with the conserved group II chaperonin fold (UniProt 'Belongs to the TCP-1 chaperonin family'; FUNCTION 'assists the folding of proteins upon ATP hydrolysis'). Retained as a molecular function, with the caveat that catalytic activity is unproven. The falcon synthesis underscores this caveat: the ATPase activity of BBS10 has not been validated and it is considered unlikely to act as a classical ATP-driven chaperonin. ATP binding is kept as a plausible domain-based MF, but no catalytic/ATP-dependent folding term is asserted. Supporting Evidence: file:human/BBS10/BBS10-deep-research-falcon.md the **ATPase activity of BBS10 has not been validated** file:human/BBS10/BBS10-deep-research-falcon.md This functional specialization positions BBS10 as a **chaperonin-like assembly factor** rather than a classical ATP-dependent molecular chaperone |
| GO:0005929 cilium | IEA GO_REF:0000044 | KEEP AS NON CORE | Summary: Subcellular-location IEA derived from UniProt 'Cell projection, cilium', itself based on PMID:19190184, which localized BBS10 to the basal body of the primary cilium in differentiating preadipocytes. BBS10 acts principally as a cytoplasmic assembly chaperone; the basal body / ciliary localization is reported in a single specialized context. Reason: The localization is supported (basal body of the primary cilium, PMID:19190184) but is not the defining feature of BBS10, whose core action is cytoplasmic chaperonin-like BBSome assembly. Keep as a non-core cellular component; the term is the parent 'cilium' rather than a more specific basal-body term. The falcon synthesis notes that chaperonin-like BBS proteins including BBS10 are generally not detected along the ciliary axoneme itself but at the basal body/pericentriolar region, so the broad 'cilium' term is at best a coarse parent of the true basal-body localization. Supporting Evidence: file:human/BBS10/BBS10-deep-research-falcon.md chaperonin-like BBS proteins including BBS10 are generally **not detected along the primary cilium** itself but are instead restricted to the ciliary base and cytoplasmic compartments where BBSome assembly is coordinated file:human/BBS10/BBS10-deep-research-falcon.md BBS10 protein has been detected at the basal body in ciliated inner medullary collecting duct (IMCD) cells |
| GO:0051131 chaperone-mediated protein complex assembly | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro2GO electronic annotation (from the BBS10-specific InterPro entry IPR042619) to the same core assembly term that is supported experimentally (IMP, PMID:20080638) and phylogenetically (IBA). Reason: Redundant with the IBA and IMP annotations to GO:0051131 but correct and well supported; represents the core function of BBS10. |
| GO:0005515 protein binding | IPI PMID:20080638 BBS6, BBS10, and BBS12 form a complex with CCT/TRiC family c... | MARK AS OVER ANNOTATED | Summary: IPI annotations documenting direct physical interactions of BBS10 with BBSome/BBS-chaperonin subunits BBS7 (Q8IWZ6), BBS9 (Q3SYG4) and BBS12 (Q6ZW61). These interactions are real and central to BBSome assembly, but 'protein binding' (GO:0005515) is an uninformative molecular function term. Reason: Per curation guidelines, GO:0005515 'protein binding' conveys no specific function. The underlying BBS7/BBS9/BBS12 interactions are better captured by the chaperone-mediated complex-assembly BP terms and by BBS-chaperonin complex membership; the bare binding term should not be treated as core. |
| GO:0005515 protein binding | IPI PMID:28514442 Architecture of the human interactome defines protein commun... | MARK AS OVER ANNOTATED | Summary: High-throughput AP-MS (BioPlex; 'Architecture of the human interactome') IPI annotation recording the BBS10-BBS7 (Q8IWZ6) physical interaction. Consistent with the curated BBS-chaperonin complex but uses the uninformative 'protein binding' term. Reason: Valid large-scale interactome detection of a known interaction, but GO:0005515 'protein binding' is non-informative and not a core function; the BBS10-BBS7 interaction is already captured by the assembly-factor role. |
| GO:0005515 protein binding | IPI PMID:33961781 Dual proteome-scale networks reveal cell-specific remodeling... | MARK AS OVER ANNOTATED | Summary: High-throughput AP-MS (BioPlex 3.0; 'Dual proteome-scale networks') IPI annotation again recording the BBS10-BBS7 (Q8IWZ6) interaction in the uninformative 'protein binding' term. Reason: Corroborates the BBS10-BBS7 interaction but adds no functional specificity; GO:0005515 should not be treated as a core annotation. |
| GO:0061629 RNA polymerase II-specific DNA-binding transcription factor binding | IPI PMID:22302990 Direct role of Bardet-Biedl syndrome proteins in transcripti... | KEEP AS NON CORE | Summary: MGI IPI annotation (partner RNF2, UniProtKB:Q99496) derived from a study whose primary focus is a nuclear role for BBS7 and its interaction with the polycomb protein RNF2; the paper states a 'similar role for other BBS proteins'. The link to BBS10 is peripheral, and a direct transcriptional role is not the established function of this chaperonin-like assembly factor. Reason: The cached abstract (full_text_available: false) centres on BBS7, not BBS10, so I cannot fully verify the BBS10-specific evidence the curator read; per 'do not overrule curators' I do not REMOVE the experimental IPI. However a direct RNA Pol II transcription-factor-binding role is not a core function of BBS10 and likely represents an over-broad/peripheral annotation, so it is retained only as non-core. |
| GO:0043254 regulation of protein-containing complex assembly | IMP PMID:22500027 Intrinsic protein-protein interaction-mediated and chaperoni... | ACCEPT | Summary: IMP from the study characterizing ordered, chaperonin-assisted assembly of the BBSome, in which the BBS-chaperonin complex (BBS6/BBS10/BBS12 + CCT/TRiC + BBS7) regulates BBS7 stability and assembly of the BBSome core (BBS7-BBS2-BBS9). Disruption of BBS10 perturbs formation of the complex. Reason: Well supported by full-text experimental evidence [PMID:22500027]: BBS10 regulates the assembly of the BBSome, a protein-containing complex. This is a faithful, somewhat more general statement of the core assembly-factor function. The falcon synthesis articulates the mechanism: the BBS-chaperonin complex stabilizes BBS7 and promotes its association with BBS2 to form the BBS2-BBS7-BBS9 core intermediate. Supporting Evidence: file:human/BBS10/BBS10-deep-research-falcon.md The BBS/CCT complex promotes BBS7 stabilization and facilitates its productive association with BBS2 to form the critical **BBS2-BBS7-BBS9 core complex** |
| GO:0051131 chaperone-mediated protein complex assembly | IMP PMID:20080638 BBS6, BBS10, and BBS12 form a complex with CCT/TRiC family c... | ACCEPT | Summary: Direct experimental (IMP) support for the core function: BBS10, as a chaperonin-like protein, mediates BBSome assembly together with BBS6, BBS12 and CCT/TRiC chaperonins; disease mutations that disrupt BBS10 interactions impair assembly [PMID:20080638]. Reason: This is the central, experimentally demonstrated function of BBS10 and the single best representative of its core biological role. |
| GO:0045494 photoreceptor cell maintenance | IMP PMID:17980398 Retinal morphology in patients with BBS1 and BBS10 related B... | KEEP AS NON CORE | Summary: IMP annotation (BHF-UCL) derived from a clinical Fourier-domain OCT imaging study documenting disrupted photoreceptor integrity and outer-retinal changes in BBS10-mutation patients. This records a loss-of-function disease phenotype rather than a direct molecular role of BBS10 in photoreceptor maintenance; the retinal degeneration is a downstream consequence of impaired BBSome assembly. Reason: The phenotype is genuine [PMID:17980398], so the involvement is retained, but BBS10 is a cytoplasmic chaperonin-like assembly factor and its effect on photoreceptors is indirect (via the BBSome). Keep as a non-core, downstream biological-process annotation rather than a core function. |
| GO:1905515 non-motile cilium assembly | IMP PMID:17980398 Retinal morphology in patients with BBS1 and BBS10 related B... | KEEP AS NON CORE | Summary: IMP annotation (BHF-UCL) to non-motile (primary) cilium assembly from the same patient OCT imaging study. BBS10 is not a structural ciliary or IFT protein; any effect on primary cilium assembly is indirect, mediated by its role in assembling the BBSome, which in turn supports ciliary membrane trafficking. Reason: Defensible as a downstream phenotypic consequence but not a direct molecular function of this assembly chaperone. The cited reference [PMID:17980398] is a clinical retinal imaging study and provides only indirect support for a primary-cilium-assembly role; keep as non-core. |
| GO:0044183 protein folding chaperone | IBA GO_REF:0000033 | NEW | Summary: Proposed molecular-function annotation reflecting BBS10's role as a chaperonin-like (group II TCP-1/CCT family) protein that binds BBSome subunits to assist their folding/assembly. Not currently in the GOA; offered as a more informative MF than the redundant 'protein binding' annotations. Reason: Captures BBS10's chaperone-like molecular activity within the BBS-chaperonin complex. Note that direct ATP-dependent folding (GO:0140662) is plausible but not experimentally proven, so the more general GO:0044183 is proposed. Based on UniProt 'Probable molecular chaperone that assists the folding of proteins upon ATP hydrolysis' and TCP-1 family membership. |
| GO:0005737 cytoplasm | IBA GO_REF:0000033 | NEW | Summary: Proposed cellular-component annotation: BBS10 acts as a cytoplasmic assembly factor, forming the BBS-chaperonin complex with CCT/TRiC and recruiting BBSome subunits prior to their delivery to the cilium. Reason: The BBS-chaperonin complex and BBSome-core assembly occur in the cytoplasm [PMID:20080638; PMID:22500027]; the cytoplasmic location is the principal site of BBS10 action and complements the (non-core) basal-body/cilium localization. The falcon synthesis places BBS10's site of action in the cytoplasmic/pericentriolar assembly zone, consistent with this CC annotation. Supporting Evidence: file:human/BBS10/BBS10-deep-research-falcon.md BBSome assembly, which occurs in the cytoplasm and at centriolar satellites before the mature BBSome is recruited to the ciliary base |
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Download this section (compressed HTML)Q: Does BBS10 possess intrinsic ATP-dependent protein-folding (chaperonin) activity, or does it act solely as a non-catalytic adaptor that recruits BBSome subunits to the CCT/TRiC chaperonin?
Q: Is BBS10 ever a transient or substoichiometric component of the assembling BBSome, or is it strictly excluded from the mature BBSome (GO:0034464)?
Q: Is the reported interaction of BBS10 with the transcriptional regulator RNF2 (PMID:22302990) a direct, functionally meaningful interaction for BBS10, or is it primarily attributable to BBS7?
Experiment: Reconstitute purified BBS10 with BBS7/BBS9/BBS12 and CCT/TRiC and assay ATP-dependent folding/assembly activity (e.g. substrate refolding, ATPase rate, BBSome-core formation) to test whether BBS10 has catalytic chaperonin activity or acts as a non-catalytic adaptor.
Hypothesis: BBS10 binds ATP via its conserved equatorial domain but functions chiefly as a CCT/TRiC-recruiting adaptor rather than as an autonomous folding chaperonin.
Type: in vitro biochemistry/reconstitution
Experiment: Quantitative interaction mapping (mutagenesis of the nucleotide-binding site and of patient variants such as R34P, V240G, S311A, S329L, D81N) coupled to BBSome-assembly readouts to define which BBS10 surfaces drive assembly versus ATP binding.
Hypothesis: Patient mutations impair BBSome assembly by disrupting BBS10 protein-protein interactions and/or overall fold rather than by abolishing ATP binding per se.
Type: structure-function mutagenesis
Experiment: Endogenous BBS10 affinity purification and size-fractionation (sucrose gradient) in ciliated human cells to determine whether BBS10 co-migrates with the mature BBSome or only with the transient BBS-chaperonin/assembly intermediate.
Hypothesis: BBS10 is present only in the BBS-chaperonin/assembly-intermediate fraction and is excluded from the mature, ciliary BBSome.
Type: biochemical fractionation/proteomics
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