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
|
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
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.
BBS10 (UniProt: Q8TAM1) encodes the Bardet-Biedl syndrome 10 protein in Homo sapiens (human) (gupta2022bardet–biedlsyndromethe pages 1-2). This protein is also known by its chromosomal designation C12orf58 and belongs to the TCP-1 chaperonin family, specifically classified within the group II chaperonins related to the CCT/TRiC (chaperonin containing TCP-1/T-complex protein-1 ring complex) family (gupta2022bardet–biedlsyndromethe pages 3-4, tian2023organizationfunctionsand pages 5-6, alvarezsatta2017bardetbiedlsyndromeas pages 2-3). The protein contains key InterPro domains including BBS10 (IPR042619), Cpn60/GroEL/TCP-1 (IPR002423), GroEL-like apical domain superfamily (IPR027409), GroEL-like equatorial superfamily (IPR027413), and TCP-1-like intermediate superfamily (IPR027410), confirming its chaperonin-like architecture (gupta2022bardet–biedlsyndromethe pages 1-2).
The primary molecular function of BBS10 is to mediate BBSome assembly through a chaperonin-like mechanism (zhang2012intrinsicproteinproteininteractionmediated pages 1-2, seo2010bbs6bbs10and pages 1-2). BBS10 is not itself a component of the mature BBSome—the octameric protein complex comprising BBS1, BBS2, BBS4, BBS5, BBS7, BBS8/TTC8, BBS9, and BBS18/BBIP1 that regulates ciliary membrane protein trafficking (tian2023organizationfunctionsand pages 1-2, tian2023organizationfunctionsand pages 5-6). Instead, BBS10 functions as part of a specialized BBS/CCT assembly machinery required for BBSome biogenesis (tian2023organizationfunctionsand pages 6-7, seo2010bbs6bbs10and pages 1-2).
BBS10 forms a higher-order complex with two other chaperonin-like BBS proteins, BBS6/MKKS and BBS12, together with six canonical CCT chaperonin subunits (CCT1, CCT2, CCT3, CCT4, CCT5, and CCT8) (seo2010bbs6bbs10and pages 2-3, seo2010bbs6bbs10and pages 1-2). This BBS/CCT complex functions as the assembly platform for the BBSome. Landmark studies by Seo et al. (2010) demonstrated through sequential affinity purification and size exclusion chromatography that BBS6, BBS10, and BBS12 associate with CCT/TRiC family chaperonins to form a complex essential for BBSome assembly (seo2010bbs6bbs10and pages 1-2). In Bbs6 null mouse tissues, BBSome subunits fail to properly associate with each other and show aberrant elution profiles, demonstrating that the chaperonin-like BBS proteins are required for BBSome formation (seo2010bbs6bbs10and pages 2-3).
The assembly mechanism operates through a stepwise process where BBS10 and its partners act as a substrate-binding unit that regulates BBS7 stability (tian2023organizationfunctionsand pages 6-7, zhang2012intrinsicproteinproteininteractionmediated pages 1-2). The BBS/CCT complex promotes BBS7 stabilization and facilitates its productive association with BBS2 to form the critical BBS2-BBS7-BBS9 core complex, which serves as the assembly intermediate upon which other BBSome subunits (BBS1, BBS4, BBS5, and BBS8) are subsequently recruited (tian2023organizationfunctionsand pages 6-7, zhang2012intrinsicproteinproteininteractionmediated pages 1-2). Zhang et al. (2012) demonstrated through characterization of BBSome assembly intermediates that the BBS-chaperonin complex plays a role in BBS7 stability, and that BBS7 interacts with BBS2 to become part of the BBSome core complex before additional subunits are incorporated (zhang2012intrinsicproteinproteininteractionmediated pages 1-2).
BBS10 is positioned functionally upstream in the assembly pathway, acting before or during the transition from the BBS-chaperonin complex to the BBS2-BBS7-BBS9 core intermediate (tian2023organizationfunctionsand pages 5-6, tian2023organizationfunctionsand pages 6-7). Recent work has also identified post-translational regulation of BBSome assembly, including ubiquitylation events that affect BBSome stability and function (tian2023organizationfunctionsand pages 2-3).
BBS10 possesses the canonical chaperonin domain architecture consisting of three functional domains: apical, intermediate, and equatorial (gupta2022bardet–biedlsyndromethe pages 5-6, alvarezsatta2017bardetbiedlsyndromeas pages 1-2). This structure is characteristic of group II chaperonins, where the apical domain typically mediates substrate interactions, the intermediate domain connects structural elements, and the equatorial domain in canonical chaperonins harbors ATP-binding and hydrolysis functions (gupta2022bardet–biedlsyndromethe pages 5-6). BBS10 protein contains ~694 amino acids in the human sequence.
Despite structural homology to the CCT family of group II chaperonins, BBS10 has diverged functionally and does not exhibit validated classical chaperonin activity (gupta2022bardet–biedlsyndromethe pages 3-4, tian2023organizationfunctionsand pages 6-7, alvarezsatta2017bardetbiedlsyndromeas pages 1-2). Key differences include:
Lack of conserved ATP-binding motifs: While canonical CCT chaperonins mediate protein folding in an ATP-dependent manner through coordinated ATP binding and hydrolysis, BBS6 and BBS12 do not contain conserved ATP-binding motifs, and the ATPase activity of BBS10 has not been validated (gupta2022bardet–biedlsyndromethe pages 3-4, tian2023organizationfunctionsand pages 6-7, alvarezsatta2017bardetbiedlsyndromeas pages 1-2).
Specialized substrate specificity: Rather than functioning as a general protein-folding machine, BBS10 acts specifically as part of the substrate-binding unit for BBSome assembly, particularly targeting BBS7 stabilization (tian2023organizationfunctionsand pages 6-7).
No autonomous chaperonin activity: The protein folding activity of the BBS/CCT complex is accomplished through the incorporated canonical CCT chaperonins rather than through intrinsic enzymatic activity of BBS10 itself (tian2023organizationfunctionsand pages 6-7, alvarezsatta2017bardetbiedlsyndromeas pages 1-2).
This functional specialization positions BBS10 as a chaperonin-like assembly factor rather than a classical ATP-dependent molecular chaperone (alvarezsatta2017bardetbiedlsyndromeas pages 1-2, alvarezsatta2017bardetbiedlsyndromeas pages 2-3).
BBS10 localizes primarily to the basal body and pericentriolar region of ciliated cells (gupta2022bardet–biedlsyndromethe pages 2-3, gupta2022bardet–biedlsyndromethe pages 5-6). Unlike core BBSome components that traffic along the cilium during intraflagellar transport (IFT), 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 (gupta2022bardet–biedlsyndromethe pages 2-3). BBS10 protein has been detected at the basal body in ciliated inner medullary collecting duct (IMCD) cells, though low endogenous protein levels have made comprehensive subcellular localization studies challenging (gupta2022bardet–biedlsyndromethe pages 5-6).
The pericentriolar localization is consistent with BBS10's role in BBSome assembly, which occurs in the cytoplasm and at centriolar satellites before the mature BBSome is recruited to the ciliary base for subsequent ciliary targeting (tian2023organizationfunctionsand pages 6-7, tian2023organizationfunctionsand pages 7-9, seo2010bbs6bbs10and pages 1-2). The spatial separation between BBS10 function (assembly at the basal body/pericentriolar zone) and BBSome function (ciliary membrane trafficking) reflects the temporal sequence of BBSome biogenesis and deployment.
BBS10 participates in the ciliary trafficking pathway indirectly by enabling assembly of the BBSome, which acts as a cargo adapter for ciliary membrane protein transport (tian2023organizationfunctionsand pages 1-2, singh2020structureandactivation pages 1-2, wingfield2018traffickingofciliary pages 1-2). The mature BBSome functions as an adaptor complex that recognizes ciliary targeting sequences on membrane proteins, particularly G-protein-coupled receptors (GPCRs), and links them to the intraflagellar transport (IFT) machinery for regulated entry into and exit from cilia (singh2020structureandactivation pages 1-2, wingfield2018traffickingofciliary pages 1-2, chou2019themoleculararchitecture pages 1-3).
The BBSome cycles through cilia via association with IFT trains, which are propelled by molecular motors (kinesin-2 for anterograde transport to the ciliary tip, dynein-2 for retrograde transport back to the cell body) along the ciliary microtubule axoneme (wingfield2018traffickingofciliary pages 1-2). Recent evidence indicates the BBSome primarily functions in the removal of specific transmembrane and peripheral membrane proteins from cilia, acting as a cargo adapter for ciliary export (wingfield2018traffickingofciliary pages 1-2). By ensuring proper BBSome formation, BBS10 indirectly enables these ciliary trafficking functions.
Through its role in BBSome assembly, BBS10 impacts multiple ciliary signaling pathways:
Hedgehog signaling: The BBSome regulates ciliary localization of Hedgehog pathway components including GPR161 and Smoothened (SMO). Loss of BBS proteins leads to ciliary dislocation of hedgehog signaling components, accounting for developmental defects and polydactyly phenotypes in BBS (tian2023organizationfunctionsand pages 2-3, tian2023organizationfunctionsand pages 1-2).
GPCR signaling: The BBSome controls ciliary trafficking of multiple GPCRs including neuropeptide Y receptor 2 (NPY2R), serotonin receptor 5-HT2CR, and leptin receptor. Mislocalization of these receptors in hypothalamic neurons may contribute to hyperphagia and obesity in BBS (tian2023organizationfunctionsand pages 2-3).
Photoreceptor homeostasis: In retinal photoreceptors, the BBSome is essential for maintaining proper protein and lipid composition of the outer segment, which is a specialized ciliary structure. BBS defects lead to rhodopsin mislocalization and photoreceptor apoptosis, causing retinal degeneration (tian2023organizationfunctionsand pages 2-3).
Recent studies suggest BBS10 may have additional pleiotropic roles beyond BBSome assembly (gupta2022bardet–biedlsyndromethe pages 7-8, gupta2022bardet–biedlsyndromethe pages 6-7):
Insulin signaling: BBS10 has been shown to participate in insulin signaling through direct interaction with the insulin receptor. Human mutant fibroblasts with BBS10 deficiency show impaired insulin signaling, with more severe defects than BBS1 mutations (gupta2022bardet–biedlsyndromethe pages 6-7). BBS10 co-immunoprecipitates with the insulin receptor, and BBS10 mutations decrease insulin receptor autophosphorylation (gupta2022bardet–biedlsyndromethe pages 6-7).
Leptin signaling: Leptin signaling is deregulated in BBS10-deficient hypothalamic-derived neurons, though whether this reflects impaired leptin receptor trafficking via BBSome abnormalities or direct regulation of leptin receptor stability by BBS10 remains unclear (gupta2022bardet–biedlsyndromethe pages 6-7).
Adipogenesis: BBS10 has been implicated in regulation of adipogenesis and metabolic processes, contributing to the obesity phenotype in BBS (tian2023organizationfunctionsand pages 2-3, gupta2022bardet–biedlsyndromethe pages 7-8).
These emerging non-ciliary functions require further validation but suggest BBS10 may have evolved additional roles beyond its primary BBSome assembly function.
BBS10 is one of the most important genes mutated in Bardet-Biedl syndrome (BBS; OMIM #209900), a rare autosomal recessive ciliopathy (alvarezsatta2017bardetbiedlsyndromeas pages 2-3). BBS10 alone accounts for approximately 20% of molecularly diagnosed BBS cases, making it second only to BBS1 (~28% of cases) in mutational frequency (tian2023organizationfunctionsand pages 5-6, alvarezsatta2017bardetbiedlsyndromeas pages 2-3). Together with BBS6/MKKS and BBS12, the three chaperonin-like BBS genes account for over 30% of the total BBS mutational burden, highlighting the critical importance of the BBSome assembly machinery in disease pathogenesis (gupta2022bardet–biedlsyndromethe pages 2-3, alvarezsatta2017bardetbiedlsyndromeas pages 2-3).
This high mutational burden is particularly striking given the extensive genetic heterogeneity of BBS, with 21-26 genes now identified (tian2023organizationfunctionsand pages 1-2, alvarezsatta2017bardetbiedlsyndromeas pages 2-3). The mutational frequency varies by population; for example, BBS10 accounts for 43% of cases in Danish cohorts but only 8.3% in Spanish cohorts, while showing the typical ~20% frequency in multiethnic cohorts (alvarezsatta2017bardetbiedlsyndromeas pages 2-3).
Approximately 100 different disease-causing variants in BBS10 have been reported, including nonsense, frameshift, missense, and splice site mutations distributed throughout the gene (gupta2022bardet–biedlsyndromethe pages 5-6, alvarezsatta2017bardetbiedlsyndromeas pages 2-3). A recurrent pathogenic allele in populations of European descent is p.Cys91Leufs*5, reaching 26-48% frequency among BBS10 mutations in these populations (alvarezsatta2017bardetbiedlsyndromeas pages 2-3). Truncating mutations affecting the intermediate and equatorial domains are predicted to disrupt regions classically responsible for ATP binding and protein interaction in canonical chaperonins, likely ablating BBS10's assembly function (gupta2022bardet–biedlsyndromethe pages 5-6).
BBS families with pathogenic variants in chaperonin-like BBS genes (BBS6, BBS10, or BBS12) generally display more severe phenotypes than families with mutations in core BBSome component genes (tian2023organizationfunctionsand pages 5-6, alvarezsatta2017bardetbiedlsyndromeas pages 1-2, alvarezsatta2017bardetbiedlsyndromeas pages 2-3). Key features include:
Earlier disease onset: BBS10 patients particularly show earlier presentation of symptoms (alvarezsatta2017bardetbiedlsyndromeas pages 2-3).
Greater prevalence of primary features: Higher frequency of all six primary diagnostic features of BBS: retinal dystrophy, obesity, polydactyly, cognitive impairment, hypogonadism, and renal anomalies (alvarezsatta2017bardetbiedlsyndromeas pages 2-3).
Severe renal involvement: Chaperonin-like BBS gene mutations correlate with more severe kidney impairment (gupta2022bardet–biedlsyndromethe pages 3-4).
Overlapping ciliopathy features: Higher frequency of features overlapping with other ciliopathies, particularly McKusick-Kaufman syndrome (MKKS) and Alström syndrome (alvarezsatta2017bardetbiedlsyndromeas pages 2-3).
The mechanistic basis for increased severity likely relates to the fact that mutations in chaperonin-like BBS proteins completely block BBSome assembly, preventing formation of any functional complexes, whereas mutations in individual BBSome subunits may allow accumulation of partially functional assembly intermediates that retain residual activity (alvarezsatta2017bardetbiedlsyndromeas pages 2-3).
BBS is characterized by the following primary features (tian2023organizationfunctionsand pages 1-2):
Secondary features include diabetes mellitus, hypertension, dental anomalies, congenital heart disease, and hepatic fibrosis (tian2023organizationfunctionsand pages 1-2). Diagnosis requires either four primary features or three primary plus two secondary features (tian2023organizationfunctionsand pages 1-2).
BBS10 belongs to the evolutionarily ancient group II chaperonin superfamily, which includes the eukaryotic CCT/TRiC complex (gupta2022bardet–biedlsyndromethe pages 3-4, tian2023organizationfunctionsand pages 5-6, alvarezsatta2017bardetbiedlsyndromeas pages 2-3). Canonical CCT chaperonins form hetero-oligomeric complexes consisting of two stacked rings, each composed of eight radially arranged subunits (CCT1-8), that mediate ATP-dependent protein folding (tian2023organizationfunctionsand pages 5-6). BBS10 has retained the characteristic three-domain chaperonin architecture (apical, intermediate, equatorial) but has undergone neofunctionalization to serve a specialized role in BBSome assembly rather than general protein folding (alvarezsatta2017bardetbiedlsyndromeas pages 1-2, alvarezsatta2017bardetbiedlsyndromeas pages 2-3).
BBS10 and other chaperonin-like BBS proteins are conserved in organisms with cilia, including vertebrates, but are absent in some ciliated organisms such as Drosophila melanogaster that lack BBS2 and BBS7 and have simplified BBSome complexes (tian2023organizationfunctionsand pages 6-7). This phylogenetic distribution suggests that the BBS/CCT assembly machinery may be most important in organisms with complex, full BBSomes requiring elaborate assembly regulation (tian2023organizationfunctionsand pages 6-7). Alternative BBSome assembly mechanisms must exist in organisms lacking BBS10 homologs (tian2023organizationfunctionsand pages 6-7).
The evolutionary relationship to canonical chaperonins but functional specialization for BBSome assembly represents an interesting example of protein evolution where structural modules are maintained but catalytic functions are lost or modified for new regulatory roles (alvarezsatta2017bardetbiedlsyndromeas pages 2-3).
Recent comprehensive reviews have synthesized current understanding of BBSome organization, functions, and mechanisms (tian2023organizationfunctionsand pages 1-2). Work on ubiquitylation of BBSome subunits has revealed additional layers of post-translational regulation affecting BBSome stability, ciliary assembly, and signaling (tian2023organizationfunctionsand pages 2-3). Clinical perspectives have been updated to reflect growing knowledge of genotype-phenotype correlations and management strategies for BBS patients (Melluso et al. 2023).
Key areas requiring further investigation include:
Precise molecular mechanism: The exact biochemical mechanism by which BBS10 and the BBS/CCT complex stabilize BBS7 and promote its association with BBS2 remains incompletely understood at the atomic level.
Non-ciliary functions: The emerging roles of BBS10 in insulin/leptin signaling and metabolic regulation require validation and mechanistic characterization to determine if these represent direct functions or downstream consequences of ciliary dysfunction.
Therapeutic targeting: Understanding BBS10 function could inform development of chaperonotherapy approaches to stabilize mutant proteins or enhance residual BBSome assembly in patients with hypomorphic alleles.
Structural biology: High-resolution structural determination of BBS10 and the BBS/CCT complex would provide atomic-level insights into the assembly mechanism and disease-causing mutations.
BBS10 (Q8TAM1) is a chaperonin-like protein belonging to the TCP-1/CCT family that serves as a critical component of the BBSome assembly machinery in humans. Its primary molecular function is to mediate BBSome biogenesis through formation of a higher-order complex with BBS6, BBS12, and CCT/TRiC chaperonins that stabilizes BBS7 and promotes formation of the BBS2-BBS7-BBS9 core complex. BBS10 localizes to the basal body and pericentriolar region where BBSome assembly occurs, distinct from the ciliary localization of mature BBSome. By enabling BBSome formation, BBS10 indirectly regulates ciliary membrane protein trafficking, GPCR signaling, hedgehog pathway activity, and photoreceptor homeostasis. Mutations in BBS10 account for ~20% of Bardet-Biedl syndrome cases and are associated with severe, early-onset ciliopathy phenotypes. The protein exemplifies evolutionary adaptation of ancient chaperonin architecture for specialized cellular regulatory functions in ciliary biology.
| Aspect | BBS10 summary | Evidence / details | Key citations |
|---|---|---|---|
| Verified identity | BBS10 encodes Bardet-Biedl syndrome 10 protein in Homo sapiens; it is a chaperonin-like BBS protein rather than a core BBSome subunit. | Reviews and gene tables consistently classify BBS10 with BBS6/MKKS and BBS12 as BBSome assembly chaperonins, distinct from the 8-subunit BBSome. This matches the UniProt description and TCP-1/CCT family assignment. | (gupta2022bardet–biedlsyndromethe pages 4-5, tian2023organizationfunctionsand pages 5-6, alvarezsatta2017bardetbiedlsyndromeas pages 2-3) |
| Primary molecular function | Mediator/regulator of BBSome assembly through a chaperonin-like role; supports formation of the BBSome rather than acting as a cargo-binding BBSome subunit itself. | BBS10 forms part of a specialized BBS/CCT assembly machinery required for BBSome biogenesis. Loss of this machinery disrupts assembly of the BBSome and destabilizes BBSome subunits. | (tian2023organizationfunctionsand pages 6-7, zhang2012intrinsicproteinproteininteractionmediated pages 1-2, seo2010bbs6bbs10and pages 1-2) |
| Protein family and structural class | Chaperonin-like protein with homology to group II chaperonins / CCT(TRiC)/TCP-1 family. | BBS10 is repeatedly described as having sequence and structural homology to CCT family chaperonins, placing it in the eukaryotic type II chaperonin lineage, but with specialized BBS-related function. | (gupta2022bardet–biedlsyndromethe pages 3-4, tian2023organizationfunctionsand pages 5-6, seo2010bbs6bbs10and pages 1-2, alvarezsatta2017bardetbiedlsyndromeas pages 2-3) |
| Domain architecture | Contains the canonical chaperonin-like apical, intermediate, and equatorial domains. | Review evidence explicitly states that BBS10 has three functional domains: apical, intermediate, and equatorial. The equatorial/intermediate region is linked to ATP-related motifs in canonical chaperonins, though bona fide ATPase activity for BBS10 remains unvalidated. | (gupta2022bardet–biedlsyndromethe pages 5-6, alvarezsatta2017bardetbiedlsyndromeas pages 1-2) |
| Functional meaning of domains | Apical domain likely contributes to client/substrate interactions; intermediate/equatorial domains retain chaperonin-like architecture but do not establish canonical ATP-dependent folding activity. | BBS10 truncating variants in the intermediate and equatorial domains are predicted to disrupt regions classically responsible for ATP binding/hydrolysis and folding in canonical chaperonins; however, reviews emphasize that BBS10 is unlikely to function as a classical ATP-driven chaperonin. | (gupta2022bardet–biedlsyndromethe pages 3-4, gupta2022bardet–biedlsyndromethe pages 5-6, alvarezsatta2017bardetbiedlsyndromeas pages 2-3) |
| ATPase / catalytic status | No confirmed classical enzymatic/chaperonin ATPase activity. | Reviews note that while canonical CCT chaperonins fold substrates in an ATP-dependent manner, the ATPase activity of BBS10 has not been validated; BBS6/BBS12 lack conserved ATP-binding features, and BBS10 is considered only partially conserved at this motif. | (gupta2022bardet–biedlsyndromethe pages 3-4, tian2023organizationfunctionsand pages 6-7, alvarezsatta2017bardetbiedlsyndromeas pages 1-2) |
| Mechanistic role in assembly | Regulates formation of the BBS-chaperonin complex and promotes early steps of BBSome assembly by enabling BBS7 stabilization and its productive association with BBS2. | A stepwise assembly model places BBS10 upstream of the BBSome core: BBS10 helps establish/organize the BBS6-BBS12-CCT system, which stabilizes BBS7 and promotes formation of the BBS2-BBS7-BBS9 core complex, followed by recruitment of additional BBSome subunits. | (tian2023organizationfunctionsand pages 6-7, zhang2012intrinsicproteinproteininteractionmediated pages 1-2, seo2010bbs6bbs10and pages 1-2) |
| Assembly pathway position | Functions at an early initiation step of BBSome biogenesis. | Because BBS6/BBS10/BBS12 account for a large fraction of BBS cases and are required before stable BBSome formation, they are inferred to act early; mechanistic work places BBS10 before or during transition from the BBS-chaperonin complex to the BBS2-BBS7-BBS9 core intermediate. | (tian2023organizationfunctionsand pages 5-6, tian2023organizationfunctionsand pages 6-7, alvarezsatta2017bardetbiedlsyndromeas pages 2-3) |
| Chaperonin complex membership | Participates in a higher-order complex with BBS6, BBS12, and CCT/TRiC family chaperonins. | Sequential purification and gel filtration identified a complex containing the three chaperonin-like BBS proteins plus multiple CCT subunits. This complex is necessary for BBSome assembly. | (seo2010bbs6bbs10and pages 2-3, seo2010bbs6bbs10and pages 1-2) |
| CCT/TRiC interaction partners | Associated with CCT1, CCT2, CCT3, CCT4, CCT5, and CCT8 in the BBS/CCT assembly complex. | Primary data and later reviews state that BBS6/BBS10/BBS12 form a complex with six canonical CCT chaperonins; this is the core evidence linking BBS10 to the TCP-1 family functionally as well as evolutionarily. | (tian2023organizationfunctionsand pages 6-7, seo2010bbs6bbs10and pages 2-3, seo2010bbs6bbs10and pages 1-2) |
| Direct/near-direct BBSome-related partners | Interacts with BBS7; reported interactions also include BBS9 and association with assembly intermediates containing BBS2. | Co-IP studies summarized in reviews found BBS10 interaction with BBS7 and BBS9; mechanistically, the chaperonin complex promotes BBS7 stability and BBS7-BBS2 association, enabling BBSome core formation. | (gupta2022bardet–biedlsyndromethe pages 3-4, tian2023organizationfunctionsand pages 6-7, seo2010bbs6bbs10and pages 2-3) |
| Role relative to BBS7 | BBS7 is a key client/assembly substrate whose stabilization depends on the BBS-chaperonin machinery involving BBS10. | The BBS-chaperonin complex plays a role in BBS7 stability; BBS7 then joins BBS2 and BBS9 to form the core intermediate. Reviews further state that BBS6/BBS10/BBS12 act as a substrate-binding unit linking CCT chaperonins to BBS7. | (gupta2022bardet–biedlsyndromethe pages 3-4, tian2023organizationfunctionsand pages 6-7, zhang2012intrinsicproteinproteininteractionmediated pages 1-2) |
| Not a structural BBSome subunit | Excluded from the mature octameric BBSome. | The mature BBSome is composed of BBS1, BBS2, BBS4, BBS5, BBS7, BBS8/TTC8, BBS9, and BBS18/BBIP1; BBS10 instead belongs to the assembly machinery. | (tian2023organizationfunctionsand pages 1-2, singh2020structureandactivation pages 1-2, tian2023organizationfunctionsand pages 5-6) |
| Subcellular localization | Best-supported localization is basal body / pericentriolar region; unlike core BBSome proteins, chaperonin-like BBS proteins are generally not detected along the primary cilium itself. | Reviews note that chaperonin-like BBS proteins have not been detected along the primary cilium, but have been found at the basal body. BBS10 protein was detected at the basal body of ciliated IMCD cells. | (gupta2022bardet–biedlsyndromethe pages 2-3, gupta2022bardet–biedlsyndromethe pages 5-6) |
| Cellular site of action | Functions mainly in the cytoplasm/pericentriolar compartment at or near the basal body, where pre-BBSome assembly is coordinated. | Because BBS10 works with CCT/TRiC and BBS7 prior to mature BBSome formation, its action is placed in the assembly zone rather than in the ciliary membrane trafficking step mediated by mature BBSome-ARL6. | (tian2023organizationfunctionsand pages 6-7, tian2023organizationfunctionsand pages 7-9, seo2010bbs6bbs10and pages 1-2) |
| Pathway context | Acts in the broader ciliary trafficking pathway by enabling assembly of the BBSome, which in turn controls ciliary membrane protein composition and signaling. | The BBSome is a ciliary transport/cargo adaptor for membrane proteins and GPCRs; therefore BBS10 affects ciliary signaling indirectly, via assembly of this transport complex. | (tian2023organizationfunctionsand pages 1-2, singh2020structureandactivation pages 1-2, wingfield2018traffickingofciliary pages 1-2) |
| Downstream biology affected through BBSome | Indirectly impacts ciliary GPCR trafficking, hedgehog signaling, photoreceptor homeostasis, renal biology, and metabolic signaling because these depend on intact BBSome function. | Reviews of BBSome biology link BBSome dysfunction to receptor mislocalization, Hedgehog defects, photoreceptor degeneration, obesity, and renal abnormalities; BBS10 contributes by being required for BBSome biogenesis. | (tian2023organizationfunctionsand pages 2-3, tian2023organizationfunctionsand pages 1-2, wingfield2018traffickingofciliary pages 1-2) |
| Non-ciliary/pleiotropic evidence | Emerging literature suggests BBS10 may have additional pleiotropic roles, but these are less established than its assembly function. | Review articles discuss roles in adipogenesis and metabolic signaling, but these are generally interpreted either as downstream consequences of BBS/ciliary dysfunction or as emerging non-ciliary functions requiring more direct validation. | (tian2023organizationfunctionsand pages 2-3, gupta2022bardet–biedlsyndromethe pages 7-8, gupta2022bardet–biedlsyndromethe pages 6-7) |
| Insulin signaling relevance | BBS10 has been linked to insulin receptor-related signaling defects in patient-derived cells. | Human mutant fibroblasts and neuronal models show impaired insulin/leptin signaling in BBS10 deficiency; this is important biologically but does not yet supersede the primary assembly role. | (gupta2022bardet–biedlsyndromethe pages 6-7) |
| Disease association | Bardet-Biedl syndrome (BBS); BBS10 is one of the most important human BBS genes. | BBS10 is a major contributor to molecularly diagnosed BBS and is repeatedly cited alongside BBS1 as among the most frequently mutated genes. | (alvarezsatta2017bardetbiedlsyndromeas pages 2-3, tian2023organizationfunctionsand pages 5-6) |
| Contribution to mutational burden | Chaperonin-like genes BBS6, BBS10, and BBS12 together account for >30% of BBS mutational load; BBS10 alone contributes ~20% of cases in many cohorts. | Multiple reviews summarize BBS10 as a major BBS gene, with frequency varying by population. | (gupta2022bardet–biedlsyndromethe pages 2-3, alvarezsatta2017bardetbiedlsyndromeas pages 2-3) |
| Genotype-phenotype severity | Variants in BBS10 are often associated with more severe phenotypes than variants in many core BBSome genes. | Reviews report earlier onset, greater prevalence of primary BBS features, and especially more severe renal/metabolic involvement for chaperonin-like BBS genes, including BBS10. | (tian2023organizationfunctionsand pages 5-6, alvarezsatta2017bardetbiedlsyndromeas pages 1-2, alvarezsatta2017bardetbiedlsyndromeas pages 2-3) |
| Variant types and recurrent alleles | Pathogenic variants include nonsense, frameshift, missense, and truncating variants distributed across the gene; a recurrent European allele is p.Cys91Leufs*5. | Reviews summarize ~100 pathogenic BBS10 variants and note population-specific recurrence patterns. Truncations affecting intermediate/equatorial domains are predicted to disrupt function strongly. | (gupta2022bardet–biedlsyndromethe pages 5-6, alvarezsatta2017bardetbiedlsyndromeas pages 2-3) |
| High-level expert consensus | Current expert consensus defines BBS10 as a TCP-1/CCT-related, chaperonin-like assembly factor for the BBSome, acting early at the basal body/pericentriolar compartment and essential for proper ciliopathy-related signaling. | This synthesis is stable across primary assembly papers and recent reviews. | (tian2023organizationfunctionsand pages 5-6, tian2023organizationfunctionsand pages 6-7, seo2010bbs6bbs10and pages 1-2) |
Table: This table summarizes the main functional, structural, localization, interaction, and disease-related features of human BBS10. It is useful as a compact evidence map linking BBS10’s chaperonin-like TCP-1/CCT ancestry to its experimentally supported role in early BBSome assembly.
References
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BBS10 (C12orf58; HGNC:26291) is a vertebrate-specific, chaperonin-like protein of the
group II / TCP-1 (CCT/TRiC) chaperonin family. It is one of three "chaperonin-like" BBS
proteins (with MKKS/BBS6 and BBS12). Together with the CCT/TRiC chaperonin and BBS7 these
form the BBS-chaperonin complex, which acts as an assembly factor (chaperone) for the
BBSome — it is NOT a stable structural subunit of the mature BBSome (GO:0034464).
PMID:20080638.
- UniProt SUBUNIT: "Component of a complex composed at least of MKKS, BBS10, BBS12, TCP1,
CCT2, CCT3, CCT4, CCT5 and CCT8" [ECO:0000269|PubMed:20080638].
- UniProt INTERACTION: BBS10 binds BBS12 (Q6ZW61), BBS7 (Q8IWZ6), BBS9 (Q3SYG4).
- Disease mutations (e.g. R34P, V240G, S311A, S329L) reduce BBS10 interaction with BBS7/BBS9
and/or BBS12, linking assembly-factor function to pathology [PMID:20080638; PMID:16582908].
- D81N mutagenesis "Greatly decreases all interactions with BBS7, BBS9 and BBS12 indicating
that this residue may be required for overall protein conformation" (UniProt FT MUTAGEN).
PMID:22500027 — full text available. This paper
characterizes the ordered, chaperonin-assisted assembly of the BBSome core
(BBS7-BBS2-BBS9), supporting the IMP annotation to regulation of protein-containing complex
assembly (GO:0043254) and chaperone-mediated protein complex assembly (GO:0051131).
[PMID:22302990 abstract] is primarily about BBS7 having a nuclear role and interacting
with the PcG protein RNF2 (Q99496). "Our data supports a similar role for other BBS proteins."
The IPI annotation of BBS10 → RNA Pol II transcription factor binding (with RNF2, UniProtKB:
Q99496), assigned by MGI, is peripheral and not a core function of BBS10. Full text not in
cache (full_text_available: false) — defer rather than remove; mark as non-core /
over-annotation candidate.
[PMID:17980398 abstract] "Retinal morphology in patients with BBS1 and BBS10 related
Bardet-Biedl Syndrome evaluated by Fourier-domain optical coherence tomography." This is a
clinical OCT imaging study describing retinal dystrophy and photoreceptor disruption in
BBS1- and BBS10-mutation patients. It documents a disease phenotype (loss-of-function ->
retinal degeneration) but does NOT provide mechanistic evidence that BBS10 protein is
directly "involved in" photoreceptor cell maintenance (GO:0045494) or "non-motile cilium
assembly" (GO:1905515) at the molecular level. These BHF-UCL IMP annotations are
phenotype-derived and represent downstream/indirect consequences via impaired BBSome
assembly, not a direct molecular role. Full text available. Treat as non-core; the cilium
assembly defect is indirect (BBS10 is an assembly chaperone, not a structural ciliary/IFT
protein).
BBS10's core, defining role is as an ATP-binding, chaperonin-like assembly factor that,
within the BBS-chaperonin complex (with MKKS/BBS6, BBS12, CCT/TRiC, BBS7), mediates assembly
of the BBSome core. BP: chaperone-mediated protein complex assembly (GO:0051131) and
regulation of protein-containing complex assembly (GO:0043254). MF: ATP binding
(GO:0005524), with probable protein-folding-chaperone activity (GO:0044183 / GO:0140662, not
experimentally proven). All ciliary/retinal phenotypes are downstream of impaired BBSome
assembly.
id: Q8TAM1
gene_symbol: BBS10
product_type: PROTEIN
status: COMPLETE
taxon:
id: NCBITaxon:9606
label: Homo sapiens
description: >-
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.
existing_annotations:
- term:
id: GO:0051131
label: chaperone-mediated protein complex assembly
evidence_type: IBA
original_reference_id: GO_REF:0000033
qualifier: involved_in
review:
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.
action: ACCEPT
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.
supported_by:
- reference_id: file:human/BBS10/BBS10-deep-research-falcon.md
supporting_text: >-
BBS10 is not itself a component of the mature BBSome
- reference_id: file:human/BBS10/BBS10-deep-research-falcon.md
supporting_text: >-
BBS10 functions as part of a specialized **BBS/CCT assembly machinery**
required for BBSome biogenesis
- term:
id: GO:0005524
label: ATP binding
evidence_type: IEA
original_reference_id: GO_REF:0000002
qualifier: enables
review:
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.
action: ACCEPT
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.
supported_by:
- reference_id: file:human/BBS10/BBS10-deep-research-falcon.md
supporting_text: >-
the **ATPase activity of BBS10 has not been validated**
- reference_id: file:human/BBS10/BBS10-deep-research-falcon.md
supporting_text: >-
This functional specialization positions BBS10 as a **chaperonin-like
assembly factor** rather than a classical ATP-dependent molecular
chaperone
- term:
id: GO:0005929
label: cilium
evidence_type: IEA
original_reference_id: GO_REF:0000044
qualifier: located_in
review:
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.
action: KEEP_AS_NON_CORE
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.
supported_by:
- reference_id: file:human/BBS10/BBS10-deep-research-falcon.md
supporting_text: >-
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
- reference_id: file:human/BBS10/BBS10-deep-research-falcon.md
supporting_text: >-
BBS10 protein has been detected at the basal body in ciliated inner
medullary collecting duct (IMCD) cells
- term:
id: GO:0051131
label: chaperone-mediated protein complex assembly
evidence_type: IEA
original_reference_id: GO_REF:0000002
qualifier: involved_in
review:
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).
action: ACCEPT
reason: >-
Redundant with the IBA and IMP annotations to GO:0051131 but correct and
well supported; represents the core function of BBS10.
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:20080638
qualifier: enables
review:
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.
action: MARK_AS_OVER_ANNOTATED
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.
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:28514442
qualifier: enables
review:
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.
action: MARK_AS_OVER_ANNOTATED
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.
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:33961781
qualifier: enables
review:
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.
action: MARK_AS_OVER_ANNOTATED
reason: >-
Corroborates the BBS10-BBS7 interaction but adds no functional specificity;
GO:0005515 should not be treated as a core annotation.
- term:
id: GO:0061629
label: RNA polymerase II-specific DNA-binding transcription factor binding
evidence_type: IPI
original_reference_id: PMID:22302990
qualifier: enables
review:
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.
action: KEEP_AS_NON_CORE
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.
- term:
id: GO:0043254
label: regulation of protein-containing complex assembly
evidence_type: IMP
original_reference_id: PMID:22500027
qualifier: acts_upstream_of_or_within
review:
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.
action: ACCEPT
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.
supported_by:
- reference_id: file:human/BBS10/BBS10-deep-research-falcon.md
supporting_text: >-
The BBS/CCT complex promotes BBS7 stabilization and facilitates its
productive association with BBS2 to form the critical **BBS2-BBS7-BBS9
core complex**
- term:
id: GO:0051131
label: chaperone-mediated protein complex assembly
evidence_type: IMP
original_reference_id: PMID:20080638
qualifier: acts_upstream_of_or_within
review:
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].
action: ACCEPT
reason: >-
This is the central, experimentally demonstrated function of BBS10 and the
single best representative of its core biological role.
- term:
id: GO:0045494
label: photoreceptor cell maintenance
evidence_type: IMP
original_reference_id: PMID:17980398
qualifier: involved_in
review:
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.
action: KEEP_AS_NON_CORE
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.
- term:
id: GO:1905515
label: non-motile cilium assembly
evidence_type: IMP
original_reference_id: PMID:17980398
qualifier: involved_in
review:
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.
action: KEEP_AS_NON_CORE
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.
- term:
id: GO:0044183
label: protein folding chaperone
evidence_type: IBA
original_reference_id: GO_REF:0000033
qualifier: enables
review:
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.
action: NEW
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.
- term:
id: GO:0005737
label: cytoplasm
evidence_type: IBA
original_reference_id: GO_REF:0000033
qualifier: located_in
review:
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.
action: NEW
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.
supported_by:
- reference_id: file:human/BBS10/BBS10-deep-research-falcon.md
supporting_text: >-
BBSome assembly, which occurs in the cytoplasm and at centriolar
satellites before the mature BBSome is recruited to the ciliary base
core_functions:
- description: >-
Chaperonin-like assembly factor that, within the cytoplasmic
BBS-chaperonin complex (with MKKS/BBS6, BBS12, CCT/TRiC and BBS7), binds
BBSome subunits and mediates ordered assembly of the BBSome core complex.
molecular_function:
id: GO:0044183
label: protein folding chaperone
directly_involved_in:
- id: GO:0051131
label: chaperone-mediated protein complex assembly
- id: GO:0043254
label: regulation of protein-containing complex assembly
locations:
- id: GO:0005737
label: cytoplasm
supported_by:
- reference_id: PMID:20080638
supporting_text: >-
a novel complex composed of three chaperonin-like BBS proteins (BBS6,
BBS10, and BBS12) and CCT/TRiC family chaperonins mediates BBSome
assembly
- reference_id: PMID:20080638
supporting_text: >-
BBS6, BBS10, and BBS12 are necessary for BBSome assembly
- reference_id: PMID:22500027
supporting_text: >-
BBS6, BBS10, and BBS12 ... interact with CCT/TRiC proteins and BBS7 to
form a complex termed the BBS-chaperonin complex. This complex is
required for BBSome assembly
- reference_id: file:human/BBS10/BBS10-uniprot.txt
supporting_text: >-
Component of a complex composed at least of MKKS, BBS10, BBS12, TCP1,
CCT2, CCT3, CCT4, CCT5 and CCT8.
- description: >-
ATP-binding group II (TCP-1/CCT) chaperonin-family protein; retains the
conserved equatorial nucleotide-binding domain presumed to power its
chaperone-assisted assembly activity (catalytic folding activity inferred,
not biochemically demonstrated).
molecular_function:
id: GO:0005524
label: ATP binding
supported_by:
- reference_id: file:human/BBS10/BBS10-uniprot.txt
supporting_text: >-
Probable molecular chaperone that assists the folding of proteins upon
ATP hydrolysis
- reference_id: file:human/BBS10/BBS10-uniprot.txt
supporting_text: Belongs to the TCP-1 chaperonin family.
proposed_new_terms: []
suggested_questions:
- question: >-
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?
- question: >-
Is BBS10 ever a transient or substoichiometric component of the assembling
BBSome, or is it strictly excluded from the mature BBSome (GO:0034464)?
- question: >-
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?
suggested_experiments:
- description: >-
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.
experiment_type: in vitro biochemistry/reconstitution
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.
- description: >-
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.
experiment_type: structure-function mutagenesis
hypothesis: >-
Patient mutations impair BBSome assembly by disrupting BBS10 protein-protein
interactions and/or overall fold rather than by abolishing ATP binding per se.
- description: >-
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.
experiment_type: biochemical fractionation/proteomics
hypothesis: >-
BBS10 is present only in the BBS-chaperonin/assembly-intermediate fraction
and is excluded from the mature, ciliary BBSome.
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: PMID:17980398
title: Retinal morphology in patients with BBS1 and BBS10 related Bardet-Biedl Syndrome
evaluated by Fourier-domain optical coherence tomography.
findings: []
reference_review:
relevance: MEDIUM
correctness: VERIFIED
review_notes: >-
PubMed-verified clinical OCT study of BBS1- and BBS10-mutation patients
showing disrupted photoreceptor integrity and outer-retinal deposits.
Supports a retinal/photoreceptor loss-of-function phenotype but provides
only indirect (phenotypic) support for the IMP photoreceptor-maintenance
and non-motile-cilium-assembly annotations; not direct molecular evidence.
- id: PMID:20080638
title: BBS6, BBS10, and BBS12 form a complex with CCT/TRiC family chaperonins and
mediate BBSome assembly.
findings: []
reference_review:
relevance: HIGH
correctness: VERIFIED
review_notes: >-
PubMed-verified key primary paper establishing that BBS6/BBS10/BBS12 form a
complex with CCT/TRiC that mediates BBSome assembly, and that BBS10 binds
BBS7/BBS9/BBS12. Directly establishes the core function. Abstract-only in
cache (full_text_available: false), but UniProt curation corroborates.
- id: PMID:22302990
title: Direct role of Bardet-Biedl syndrome proteins in transcriptional regulation.
findings: []
reference_review:
relevance: LOW
correctness: VERIFIED
review_notes: >-
PubMed-verified; primarily about a nuclear role for BBS7 and its interaction
with the polycomb protein RNF2. The BBS10-specific transcription-factor-binding
evidence is peripheral and the abstract is BBS7-centric (full text not in
cache), so the BBS10 GO:0061629 annotation is treated as non-core, not removed.
- id: PMID:22500027
title: Intrinsic protein-protein interaction-mediated and chaperonin-assisted sequential
assembly of stable bardet-biedl syndrome protein complex, the BBSome.
findings: []
reference_review:
relevance: HIGH
correctness: VERIFIED
review_notes: >-
PubMed-verified, full text available. Characterizes ordered, chaperonin-assisted
BBSome assembly; BBS-chaperonin complex (BBS6/BBS10/BBS12 + CCT/TRiC + BBS7)
is required for assembly and BBS7 stability. Supports GO:0043254 and GO:0051131.
- id: PMID:28514442
title: Architecture of the human interactome defines protein communities and disease
networks.
findings: []
reference_review:
relevance: LOW
correctness: VERIFIED
review_notes: >-
PubMed-verified BioPlex high-throughput AP-MS interactome paper; supports the
BBS10-BBS7 physical interaction but yields only the uninformative
'protein binding' annotation.
- id: PMID:33961781
title: Dual proteome-scale networks reveal cell-specific remodeling of the human
interactome.
findings: []
reference_review:
relevance: LOW
correctness: VERIFIED
review_notes: >-
PubMed-verified BioPlex 3.0 interactome paper; corroborates the BBS10-BBS7
interaction but contributes only the non-informative 'protein binding' term.
- id: file:human/BBS10/BBS10-deep-research-falcon.md
title: Falcon deep research report for BBS10
findings: []
reference_review:
relevance: HIGH
correctness: UNVERIFIED
review_notes: >-
LLM-synthesized (Edison/falcon) deep-research summary; correctness UNVERIFIED
as for any LLM synthesis. BBS10-chaperonin-specific claims that are
well-anchored and corroborated by primary literature: BBS10 is NOT a subunit
of the mature octameric BBSome but a chaperonin-like assembly factor that, with
BBS6/MKKS and BBS12 plus CCT/TRiC subunits (CCT1-8), forms the BBS/CCT
machinery required for BBSome biogenesis (Seo 2010 / PMID:20080638, Zhang 2012
/ PMID:22500027); the complex stabilizes BBS7 and promotes the
BBS2-BBS7-BBS9 core; the ATPase activity of BBS10 has NOT been validated and
it is unlikely to act as a classical ATP-driven chaperonin; localization is at
the basal body/pericentriolar region and chaperonin-like BBS proteins are
generally not detected along the primary cilium. CAUTION (BBSome/CCT
over-generalization to be read skeptically, not transferred to BBS10 as fact):
claims about generic group-II/CCT three-domain ATP-dependent folding mechanism
are framed as canonical-chaperonin background, not demonstrated for BBS10; the
emerging non-ciliary roles (direct insulin-receptor binding, leptin signaling,
adipogenesis) are explicitly flagged in the report as requiring further
validation and are not used here to alter any annotation.