B9D1

Summary: B9D1 associates with B9D2 within the B9-domain complex.

Reason: The recorded partner Q9BPU9 is B9D2. Human-protein coimmunoprecipitation and three-hybrid experiments support an MKS1–B9D2–B9D1 subcomplex, with B9D2 linking the other two proteins (PMID:32726168). This association supports complex membership; it does not establish an independent adaptor activity for B9D1. The generic interaction is retained alongside the more informative complex and localization annotations. The original screen supplement for this individual pair was not independently inspected.

Summary: B9D1 associates with B9D2 within the B9-domain complex.

Reason: The recorded partner Q9BPU9 is B9D2. Human-protein coimmunoprecipitation and three-hybrid experiments support an MKS1–B9D2–B9D1 subcomplex, with B9D2 linking the other two proteins (PMID:32726168). This association supports complex membership; it does not establish an independent adaptor activity for B9D1. The generic interaction is retained alongside the more informative complex and localization annotations. The original screen supplement for this individual pair was not independently inspected.

Summary: B9D1 associates with B9D2 within the B9-domain complex.

Reason: The recorded partner Q9BPU9 is B9D2. Human-protein coimmunoprecipitation and three-hybrid experiments support an MKS1–B9D2–B9D1 subcomplex, with B9D2 linking the other two proteins (PMID:32726168). This association supports complex membership; it does not establish an independent adaptor activity for B9D1. The generic interaction is retained alongside the more informative complex and localization annotations. The inspected experiments use cell lysates rather than isolated purified binary binding.

Summary: B9D1 associates with B9D2 within the B9-domain complex.

Reason: The recorded partner Q9BPU9 is B9D2. Human-protein coimmunoprecipitation and three-hybrid experiments support an MKS1–B9D2–B9D1 subcomplex, with B9D2 linking the other two proteins (PMID:32726168). This association supports complex membership; it does not establish an independent adaptor activity for B9D1. The generic interaction is retained alongside the more informative complex and localization annotations. The original screen supplement for this individual pair was not independently inspected.

Summary: B9D1 associates with B9D2 within the B9-domain complex.

Reason: The recorded partner Q9BPU9 is B9D2. Human-protein coimmunoprecipitation and three-hybrid experiments support an MKS1–B9D2–B9D1 subcomplex, with B9D2 linking the other two proteins (PMID:32726168). This association supports complex membership; it does not establish an independent adaptor activity for B9D1. The generic interaction is retained alongside the more informative complex and localization annotations. The original screen supplement for this individual pair was not independently inspected. PMID:41039152 corrects a duplicated loss-function equation in the source paper, without withdrawing this interaction.

Summary: B9D1 has experimentally supported centrosomal localization.

Reason: PMID:19208769 reports basal-body and ciliary localization of human B9-domain proteins. Its figure caption describes tagged human constructs in mouse IMCD3 cells. The centrosomal IDA is compatible with the specialized transition-zone role; the available evidence does not exclude a broader centrosomal pool.

Summary: A cytosolic B9D1 pool is compatible with assembly of the ciliary gate.

Reason: B9D1 is a soluble component recruited into the MKS transition-zone complex (PMID:22179047; PMID:32726168). The Reactome events place the protein in a cytosolic cellular context. Those events assign RAB8A nucleotide exchange to RAB3IP and vesicle recruitment to other machinery; they do not establish either molecular activity for B9D1.

Summary: A cytosolic B9D1 pool is compatible with assembly of the ciliary gate.

Reason: B9D1 is a soluble component recruited into the MKS transition-zone complex (PMID:22179047; PMID:32726168). The Reactome events place the protein in a cytosolic cellular context. Those events assign RAB8A nucleotide exchange to RAB3IP and vesicle recruitment to other machinery; they do not establish either molecular activity for B9D1.

Summary: A cytosolic B9D1 pool is compatible with assembly of the ciliary gate.

Reason: B9D1 is a soluble component recruited into the MKS transition-zone complex (PMID:22179047; PMID:32726168). The Reactome events place the protein in a cytosolic cellular context. Those events assign RAB8A nucleotide exchange to RAB3IP and vesicle recruitment to other machinery; they do not establish either molecular activity for B9D1.

Summary: Ciliary transition zone specifies the principal functional ciliary compartment.

Reason: Tagged human B9D1 localizes to the transition zone in RPE1 cells (PMID:32726168), consistent with the transition-zone complex described in PMID:22179047. This anatomical compartment is part of the cilium and provides a more precise location for the electronic annotation. The destination is already represented by other transition-zone annotations; this refines the existing broad source row rather than adding a new location assertion.

Proposed replacements: ciliary transition zone

Summary: The historically reported axonemal localization is retained as non-core.

Reason: UniProt explicitly attributes this localization to PMID:19208769. Its Figure 2B caption describes GFP-tagged human B9-domain proteins in mouse IMCD3 cells colocalizing with acetylated-tubulin staining of the ciliary axoneme. The cached abstract alone supports only basal-body and ciliary localization. This tagged-protein observation is retained as non-core with that specificity limit; it does not establish endogenous B9D1 incorporation into axonemal microtubules. The membrane-to-axoneme position of the transition-zone complex in PMID:41165761 does not by itself invalidate the older observation. Full experimental details and original images were not independently inspected.

Summary: B9D1 supports Smoothened signaling through ciliary compartment organization.

Reason: Mouse B9d1 loss disrupts ciliary signaling-protein localization and Hedgehog responses (PMID:21763481; PMID:22179047). This is consistent with the MKS complex maintaining a functional ciliary signaling compartment. The pathway phenotype does not establish that B9D1 is itself a ligand receptor.

Summary: B9D1 supports Smoothened signaling through ciliary compartment organization.

Reason: Mouse B9d1 loss disrupts ciliary signaling-protein localization and Hedgehog responses (PMID:21763481; PMID:22179047). This is consistent with the MKS complex maintaining a functional ciliary signaling compartment. The pathway phenotype does not establish that B9D1 is itself a ligand receptor.

Summary: The transferred receptor activity conflates ciliary signaling support with ligand recognition.

Reason: GO:0008158 requires Hedgehog-family ligand recognition coupled to signaling across a membrane. The mouse B9d1 donor experiment in PMID:21763481 instead tests a Smoothened agonist: mutant fibroblasts retain cilia but fail to localize Smoothened there and show impaired Gli1/Ptch1 responses. The complete available Methods and Results support a ciliary protein-localization mechanism, without demonstrating Hedgehog binding or receptor activity by B9d1. Together with the established B9-domain gate-complex role, this supports removing the human IEA/ISS molecular-function transfer. The existing Smoothened-pathway annotations are retained as non-core. Original images and supplements were not independently inspected.

Summary: The transferred receptor activity conflates ciliary signaling support with ligand recognition.

Reason: GO:0008158 requires Hedgehog-family ligand recognition coupled to signaling across a membrane. The mouse B9d1 donor experiment in PMID:21763481 instead tests a Smoothened agonist: mutant fibroblasts retain cilia but fail to localize Smoothened there and show impaired Gli1/Ptch1 responses. The complete available Methods and Results support a ciliary protein-localization mechanism, without demonstrating Hedgehog binding or receptor activity by B9d1. Together with the established B9-domain gate-complex role, this supports removing the human IEA/ISS molecular-function transfer. The existing Smoothened-pathway annotations are retained as non-core. Original images and supplements were not independently inspected.

Summary: B9D1 can associate with the membrane through the transition-zone complex.

Reason: GO:0016020 includes proteins and complexes attached to the lipid bilayer, so solubility and absence of a transmembrane helix do not by themselves contradict this term. B9D1 belongs to the soluble B9 complex at the transition zone (PMID:22179047; PMID:32726168). PMID:41165761 reports that this complex associates with membrane protein TMEM67 and supports its transition-zone localization. Its named coimmunoprecipitation partners are B9D2 and MKS1, not an isolated B9D1–TMEM67 pair. The broad membrane annotation is retained as non-core on this complex-mediated association; direct B9D1 lipid binding, a transmembrane topology or direct B9D1–TMEM67 binding is not asserted. The more informative core location remains the ciliary transition zone.

Summary: The ciliary transition zone is a core B9D1 location.

Reason: Tagged human B9D1 localizes to the transition zone in control RPE1 cells and loses that localization in MKS1- or B9D2-knockout cells (PMID:32726168). The experiments used tagged B9D1 because suitable endogenous antibodies were unavailable. PMID:22179047 also reports interdependent transition-zone localization of B9D1, TMEM231 and CC2D2A.

Summary: The ciliary transition zone is a core B9D1 location.

Reason: Tagged human B9D1 localizes to the transition zone in control RPE1 cells and loses that localization in MKS1- or B9D2-knockout cells (PMID:32726168). The experiments used tagged B9D1 because suitable endogenous antibodies were unavailable. PMID:22179047 also reports interdependent transition-zone localization of B9D1, TMEM231 and CC2D2A.

Summary: The ciliary transition zone is a core B9D1 location.

Reason: Tagged human B9D1 localizes to the transition zone in control RPE1 cells and loses that localization in MKS1- or B9D2-knockout cells (PMID:32726168). The experiments used tagged B9D1 because suitable endogenous antibodies were unavailable. PMID:22179047 also reports interdependent transition-zone localization of B9D1, TMEM231 and CC2D2A.

Summary: B9D1 is a component of the MKS transition-zone complex.

Reason: The nine-protein ciliary gate complex described in PMID:22179047 contains B9D1. Human-protein experiments resolve the MKS1–B9D2–B9D1 subcomplex (PMID:32726168), independently supporting the annotated complex membership. These experiments do not imply direct pairwise binding between every member of the larger assembly.

Summary: B9D1 is a component of the MKS transition-zone complex.

Reason: The nine-protein ciliary gate complex described in PMID:22179047 contains B9D1. Human-protein experiments resolve the MKS1–B9D2–B9D1 subcomplex (PMID:32726168), independently supporting the annotated complex membership. These experiments do not imply direct pairwise binding between every member of the larger assembly.

Summary: B9D1 is a component of the MKS transition-zone complex.

Reason: The nine-protein ciliary gate complex described in PMID:22179047 contains B9D1. Human-protein experiments resolve the MKS1–B9D2–B9D1 subcomplex (PMID:32726168), independently supporting the annotated complex membership. These experiments do not imply direct pairwise binding between every member of the larger assembly.

Summary: B9D1 is a component of the MKS transition-zone complex.

Reason: The nine-protein ciliary gate complex described in PMID:22179047 contains B9D1. Human-protein experiments resolve the MKS1–B9D2–B9D1 subcomplex (PMID:32726168), independently supporting the annotated complex membership. These experiments do not imply direct pairwise binding between every member of the larger assembly.

Summary: Experimental localization supports a B9D1 pool at the ciliary basal body.

Reason: PMID:19208769 reports basal-body localization of the human B9-domain proteins, consistent with their role in cilium formation. Its tagged-human-protein microscopy includes mouse IMCD3 cells. More precise transition-zone localization in later work does not negate the basal-body IDA; the individual GO_REF:0000052 immunofluorescence images were not independently inspected.

Summary: Experimental localization supports a B9D1 pool at the ciliary basal body.

Reason: PMID:19208769 reports basal-body localization of the human B9-domain proteins, consistent with their role in cilium formation. Its tagged-human-protein microscopy includes mouse IMCD3 cells. More precise transition-zone localization in later work does not negate the basal-body IDA; the individual GO_REF:0000052 immunofluorescence images were not independently inspected.

Summary: B9D1 contributes to cilium assembly as part of the ciliary gate machinery.

Reason: Disruption of human MKSR1/B9D1 caused ciliogenesis defects in PMID:19208769. Human B9D1-knockout RPE1 cells in PMID:41165761 also show reduced ciliogenesis and impaired CP110 removal. B9D1 complex assembly and localization provide a direct ciliary-structure role, independently corroborating the inherited process assertion. The newer detailed vesicle experiments mainly concern B9D2 and should not be relabeled B9D1 assays. The reported human B9D1 knockout and CP110 results were read in the full-text Results and Methods; the original supplementary images were not independently inspected.

Summary: B9D1 contributes to cilium assembly as part of the ciliary gate machinery.

Reason: Disruption of human MKSR1/B9D1 caused ciliogenesis defects in PMID:19208769. Human B9D1-knockout RPE1 cells in PMID:41165761 also show reduced ciliogenesis and impaired CP110 removal. B9D1 complex assembly and localization provide a direct ciliary-structure role, independently corroborating the inherited process assertion. The newer detailed vesicle experiments mainly concern B9D2 and should not be relabeled B9D1 assays. The reported human B9D1 knockout and CP110 results were read in the full-text Results and Methods; the original supplementary images were not independently inspected.

Summary: B9D1 contributes to cilium assembly as part of the ciliary gate machinery.

Reason: Disruption of human MKSR1/B9D1 caused ciliogenesis defects in PMID:19208769. Human B9D1-knockout RPE1 cells in PMID:41165761 also show reduced ciliogenesis and impaired CP110 removal. B9D1 complex assembly and localization provide a direct ciliary-structure role, independently corroborating the inherited process assertion. The newer detailed vesicle experiments mainly concern B9D2 and should not be relabeled B9D1 assays. The original donor Q9NXB0 is human MKS1, a related B9-domain subunit, rather than a mouse B9D1 ortholog. The reported human B9D1 knockout and CP110 results were read in the full-text Results and Methods; the original supplementary images were not independently inspected.

Summary: B9D1 contributes to cilium assembly as part of the ciliary gate machinery.

Reason: Disruption of human MKSR1/B9D1 caused ciliogenesis defects in PMID:19208769. Human B9D1-knockout RPE1 cells in PMID:41165761 also show reduced ciliogenesis and impaired CP110 removal. B9D1 complex assembly and localization provide a direct ciliary-structure role, independently corroborating the inherited process assertion. The newer detailed vesicle experiments mainly concern B9D2 and should not be relabeled B9D1 assays. The reported human B9D1 knockout and CP110 results were read in the full-text Results and Methods; the original supplementary images were not independently inspected.

Summary: B9D1 helps establish the protein assembly at the ciliary transition zone.

Reason: PMID:22179047 reports that B9D1, TMEM231 and CC2D2A transition-zone localization is interdependent. Human B9-domain complex formation and localization experiments provide complementary support (PMID:32726168). The process reflects participation in building the gate assembly; B9D1 is not merely a transported cargo in this context.