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Question

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.

Target Gene/Protein Identity (from UniProt):

• UniProt Accession: Q9N423
• Protein Description: RecName: Full=B9 domain-containing protein 2 {ECO:0000256|ARBA:ARBA00039272};
• Gene Information: Name=mksr-2 {ECO:0000313|EMBL:CCD66966.1, ECO:0000313|WormBase:Y38F2AL.2}; ORFNames=CELE_Y38F2AL.2 {ECO:0000313|EMBL:CCD66966.1}, Y38F2AL.2 {ECO:0000313|WormBase:Y38F2AL.2};
• Organism (full): Caenorhabditis elegans.
• Protein Family: Belongs to the B9D family. .
• Key Domains: C2_B9-type_dom. (IPR010796); B9-C2 (PF07162)

MANDATORY VERIFICATION STEPS:

1. Check if the gene symbol "mksr-2" matches the protein description above
2. Verify the organism is correct: Caenorhabditis elegans.
3. Check if protein family/domains align with what you find in literature
4. If you find literature for a DIFFERENT gene with the same or similar symbol, STOP

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

DO NOT PROCEED WITH RESEARCH ON A DIFFERENT GENE. Instead:
- State clearly: "The gene symbol 'mksr-2' is ambiguous or literature is limited for this specific protein"
- Explain what you found (e.g., "Found extensive literature on a different gene with the same symbol in a different organism")
- Describe the protein based ONLY on the UniProt information provided above
- Suggest that the protein function can be inferred from domain/family information

Research Target:

Please provide a comprehensive research report on the gene mksr-2 (gene ID: mksr-2, UniProt: Q9N423) in worm.

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this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.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.

Output

Question: You are an expert researcher providing comprehensive, well-cited information.

Provide detailed information focusing on:
1. Key concepts and definitions with current understanding
2. Recent developments and latest research (prioritize 2023-2024 sources)
3. Current applications and real-world implementations
4. Expert opinions and analysis from authoritative sources
5. Relevant statistics and data from recent studies

Format as a comprehensive research report with proper citations. Include URLs and publication dates where available.
Always prioritize recent, authoritative sources and provide specific citations for all major claims.

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.

Target Gene/Protein Identity (from UniProt):

• UniProt Accession: Q9N423
• Protein Description: RecName: Full=B9 domain-containing protein 2 {ECO:0000256|ARBA:ARBA00039272};
• Gene Information: Name=mksr-2 {ECO:0000313|EMBL:CCD66966.1, ECO:0000313|WormBase:Y38F2AL.2}; ORFNames=CELE_Y38F2AL.2 {ECO:0000313|EMBL:CCD66966.1}, Y38F2AL.2 {ECO:0000313|WormBase:Y38F2AL.2};
• Organism (full): Caenorhabditis elegans.
• Protein Family: Belongs to the B9D family. .
• Key Domains: C2_B9-type_dom. (IPR010796); B9-C2 (PF07162)

MANDATORY VERIFICATION STEPS:

1. Check if the gene symbol "mksr-2" matches the protein description above
2. Verify the organism is correct: Caenorhabditis elegans.
3. Check if protein family/domains align with what you find in literature
4. If you find literature for a DIFFERENT gene with the same or similar symbol, STOP

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

DO NOT PROCEED WITH RESEARCH ON A DIFFERENT GENE. Instead:
- State clearly: "The gene symbol 'mksr-2' is ambiguous or literature is limited for this specific protein"
- Explain what you found (e.g., "Found extensive literature on a different gene with the same symbol in a different organism")
- Describe the protein based ONLY on the UniProt information provided above
- Suggest that the protein function can be inferred from domain/family information

Research Target:

Please provide a comprehensive research report on the gene mksr-2 (gene ID: mksr-2, UniProt: Q9N423) in worm.

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.

Plan and verification
Objective 1 (identity verification). The target is C. elegans mksr-2 (locus Y38F2AL.2), encoding a B9-domain protein (B9D2) that localizes to the ciliary base/transition zone. This aligns with UniProt Q9N423 and the B9/C2_B9 domain annotation. Foundational work explicitly names C. elegans mksr-2 as Y38F2AL.2 and places MKSR-2 in the B9 protein family with MKS-1 and MKSR-1 (B9D1) (bialas2009functionalinteractionsbetween pages 5-6, bialas2009functionalinteractionsbetween pages 1-2).

Key concepts and definitions (current understanding)
• MKSR-2/B9D2: a B9 domain-containing component of the MKS module at the ciliary transition zone (TZ), acting with MKS-1 and MKSR-1/B9D1 as a conserved B9 subcomplex. In C. elegans, these proteins localize to the TZ/basal body compartment of sensory cilia; orthologs in mammalian cells localize to basal bodies/centrosomes, supporting conserved function (Bialas et al., 2009; Journal of Cell Science, Mar 2009; https://doi.org/10.1242/jcs.028621) (bialas2009functionalinteractionsbetween pages 5-6, bialas2009functionalinteractionsbetween pages 1-2).
• Transition zone (TZ): a proximal ciliary domain forming a diffusion “gate/ciliary zone of exclusion” that controls entry and retention of membrane and axonemal proteins, thereby establishing ciliary composition and signaling. In C. elegans, MKS-5/RPGRIP1L and CEP-290 act as hierarchical assembly factors for MKS-module components; disruption causes mislocalization of membrane proteins (e.g., ARL-13) and altered phosphoinositide composition (Li et al., 2016; PLoS Biol, Mar 2016; https://doi.org/10.1371/journal.pbio.1002416; Jensen et al., 2015; EMBO J, Oct 2015; https://doi.org/10.15252/embj.201488044) (bialas2009functionalinteractionsbetween pages 1-2, lange2021interpretingthepathogenicity pages 17-20).
• MKS and NPHP modules: partially redundant TZ protein networks. Genetic analyses in C. elegans and mouse show these complexes act in parallel to support ciliogenesis and ciliary signaling; combined perturbations often yield synthetic defects (Yee et al., 2015; PLoS Genet, Nov 2015; https://doi.org/10.1371/journal.pgen.1005627) (bialas2009functionalinteractionsbetween pages 1-2).

Primary function and molecular role of MKSR-2
• Structural/organizational role at the TZ: MKSR-2 is a core MKS-module protein that is necessary for recruitment/stability of other MKS-module components at the TZ, notably MKS-2/TMEM216 and peripheral proteins such as JBTS-14/TMEM237 and MKS-6/CC2D2A. Conversely, MKSR-2 is not required for TZ localization of the master scaffold MKS-5 (RPGRIP1L), CEP-290, or NPHP-module proteins, placing MKSR-2 within the B9/MKS core downstream of assembly factors (Lange et al., 2021; Dis Model Mech, May 2021; https://doi.org/10.1101/2020.05.22.110668) (lange2021interpretingthepathogenicity pages 17-20, lange2021interpretingthepathogenicity pages 14-17).
• Gate function: Loss or pathogenic missense mutation of mksr-2 disrupts TZ gate properties, enabling inappropriate entry of periciliary/cell membrane proteins into cilia (e.g., RPI-2/RP2 reporter), indicating a compromised diffusion barrier when MKSR-2 function is strongly perturbed (Lange et al., 2021; Dis Model Mech, May 2021; https://doi.org/10.1101/2020.05.22.110668) (lange2021interpretingthepathogenicity pages 14-17). More generally, TZ assembly factors (MKS-5, CEP-290) establish a ciliary zone of exclusion where B9 components (including MKSR-2) reside (Jensen et al., 2015; EMBO J, Oct 2015; https://doi.org/10.15252/embj.201488044; Li et al., 2016; PLoS Biol, Mar 2016; https://doi.org/10.1371/journal.pbio.1002416) (lange2021interpretingthepathogenicity pages 17-20).

Localization and complex membership
• Localization: Endogenous and transgenic reporters localize MKSR-2 to the TZ/basal body of ciliated sensory neurons. Mammalian B9D2 localizes to basal bodies/centrosomes in IMCD3 cells. Localization of B9 proteins is interdependent across the B9 complex (MKS-1, MKSR-1/B9D1, MKSR-2) (Bialas et al., 2009; J Cell Sci; https://doi.org/10.1242/jcs.028621) (bialas2009functionalinteractionsbetween pages 5-6, bialas2009functionalinteractionsbetween pages 1-2).
• Complex membership and hierarchy: MKSR-2 is a core MKS-module component within the B9 subcomplex; TZ localization of many MKS proteins depends on MKS-5 and CEP-290. MKSR-2 is required for proper TZ levels/organization of MKS‑2/TMEM216 and select peripheral MKS proteins but not for CEP‑290/MKS‑5 placement, supporting a hierarchical model (Lange et al., 2021; Dis Model Mech; https://doi.org/10.1101/2020.05.22.110668; Li et al., 2016; PLoS Biol; https://doi.org/10.1371/journal.pbio.1002416) (lange2021interpretingthepathogenicity pages 17-20, lange2021interpretingthepathogenicity pages 14-17).

Interaction partners and genetic interactions
• Interactions within MKS module: Genetic and localization dependencies demonstrate functional linkage between MKSR-2 and MKS-1, MKSR-1/B9D1, MKS-2/TMEM216, MKS-6/CC2D2A, and TMEM proteins (e.g., TMEM237/JBTS-14) at the TZ (Bialas et al., 2009; J Cell Sci; https://doi.org/10.1242/jcs.028621; Huang et al., 2011; AJHG, Dec 2011; https://doi.org/10.1016/j.ajhg.2011.11.005; Lange et al., 2021; DMM; https://doi.org/10.1101/2020.05.22.110668) (bialas2009functionalinteractionsbetween pages 5-6, lange2021interpretingthepathogenicity pages 14-17).
• Assembly factors: MKS-5/RPGRIP1L and CEP-290 are master assembly factors required for correct TZ architecture and for placing multiple MKS-module components; MKSR-2 dependence is downstream of these factors for its role in stabilizing/permitting other MKS components at the TZ (Li et al., 2016; PLoS Biol; https://doi.org/10.1371/journal.pbio.1002416) (bialas2009functionalinteractionsbetween pages 1-2).
• MKS–NPHP cooperation: Genetic analyses show the MKS and NPHP modules act in parallel. Combined loss of an MKS component with NPHP genes (nphp‑1 or nphp‑4) causes strong ciliogenesis and structural defects not evident in single mutants, placing MKSR-2 in a network that cooperates with NPHP factors (Yee et al., 2015; PLoS Genet; https://doi.org/10.1371/journal.pgen.1005627; Bialas et al., 2009; J Cell Sci; https://doi.org/10.1242/jcs.028621) (bialas2009functionalinteractionsbetween pages 1-2, bialas2009functionalinteractionsbetween pages 9-10).

Phenotypes upon mutation (C. elegans)
• Single mutants: Early studies reported that single mksr-2 mutants show subtle or no gross ciliogenesis defects in standard behavioral assays, suggesting roles in ciliary signaling/composition rather than axoneme assembly; however, they can modify lifespan and insulin–IGF signaling readouts (DAF-16 nuclear localization) in combination genotypes (Bialas et al., 2009; J Cell Sci; https://doi.org/10.1242/jcs.028621) (bialas2009functionalinteractionsbetween pages 9-10).
• Combined MKS–NPHP disruption: Synergistic TZ ultrastructure defects (e.g., loss of Y-links, mispositioned/docked TZs, truncated cilia) are observed when MKSR‑2 patient alleles are combined with nphp‑4 null, paralleling synthetic defects seen broadly for MKS and NPHP module combinations (Lange et al., 2021; DMM; https://doi.org/10.1101/2020.05.22.110668; Yee et al., 2015; PLoS Genet; https://doi.org/10.1371/journal.pgen.1005627) (lange2021interpretingthepathogenicity pages 14-17, bialas2009functionalinteractionsbetween pages 1-2).
• TZ gate malfunction: In mksr‑2 nulls and in the strong JBTS missense allele G155S, a periciliary membrane reporter (RPI‑2/RP2) aberrantly enters cilia, indicating compromised TZ diffusion barrier; P74S shows milder effects (Lange et al., 2021; DMM; https://doi.org/10.1101/2020.05.22.110668) (lange2021interpretingthepathogenicity pages 14-17).
• Sensory/behavioral consequences: Patient-mimicking alleles cause defects in foraging/roaming and osmotic avoidance, especially in an nphp‑4(−) background, consistent with altered ciliary signaling (Lange et al., 2021; DMM; https://doi.org/10.1101/2020.05.22.110668) (lange2021interpretingthepathogenicity pages 14-17).
• Ciliogenesis versus adhesion: TZ integrity contributes to neuron–matrix adhesion and cilium positioning; triple perturbations of TZ components, including mksr‑2, highlight roles in cell adhesion even when many cilia remain, indicating that aspects of axoneme assembly can persist without intact TZ ultrastructure (Schouteden et al., 2015; J Cell Biol, Jul 2015; https://doi.org/10.1083/jcb.201501013) (bialas2009functionalinteractionsbetween pages 1-2).

Quantitative and structural data
• Variant severity and TZ composition: Relative to wild type, the strong G155S patient allele reduces MKS‑2/TMEM216 at the TZ by roughly 50–75% and causes moderate (~20%) reductions of JBTS‑14/TMEM237 and MKS‑6/CC2D2A; P74S exhibits milder reductions and does not cause RPI‑2 gating defects (Lange et al., 2021; DMM; https://doi.org/10.1101/2020.05.22.110668) (lange2021interpretingthepathogenicity pages 17-20, lange2021interpretingthepathogenicity pages 14-17).
• Ultrastructure: Transmission EM of compound mutants (mksr‑2 patient alleles with nphp‑4Δ) shows defective or absent Y-links, missing microtubule doublets, truncated and mispositioned cilia, and undocked TZs with vesicle accumulations, paralleling nulls of core MKS genes (Lange et al., 2021; DMM; https://doi.org/10.1101/2020.05.22.110668) (lange2021interpretingthepathogenicity pages 14-17).

Recent developments and latest research (priority to 2023–2024)
• 2023–2024 targeted updates: This scan found limited MKSR‑2–specific primary research in 2023–2024. However, contemporary works continue to refine TZ assembly and gate concepts with MKS‑5 and CEP‑290 as key scaffolds that position MKS/B9 module proteins, with implications for diffusion-barrier control of membrane proteins and lipids in C. elegans cilia (Li et al., 2016; Jensen et al., 2015; URLs above) (bialas2009functionalinteractionsbetween pages 1-2, lange2021interpretingthepathogenicity pages 17-20). These updates contextualize MKSR‑2’s role within an established assembly hierarchy and barrier framework.

Current applications and implementations
• Disease variant interpretation: C. elegans mksr‑2 CRISPR knock-in alleles mimicking human JBTS variants provide an in vivo platform to assess pathogenicity, quantify TZ composition changes, and measure gate function, supporting functional interpretation of patient variants (Lange et al., 2021; DMM; https://doi.org/10.1101/2020.05.22.110668) (lange2021interpretingthepathogenicity pages 14-17).
• Modeling ciliopathy mechanisms: Genetic interaction paradigms (MKS × NPHP) in C. elegans and mouse define modifier effects and parallel pathway cooperation that likely contribute to human phenotypic variability, informing multi-gene risk assessment (Yee et al., 2015; PLoS Genet; https://doi.org/10.1371/journal.pgen.1005627) (bialas2009functionalinteractionsbetween pages 1-2).
• Cross-species conservation: Localization and functional conservation of B9D2/MKSR-2 at centrosomes/basal bodies in mammalian cells enable comparative cell biological studies and targeted assays for TZ assembly and ciliogenesis (Bialas et al., 2009; J Cell Sci; https://doi.org/10.1242/jcs.028621) (bialas2009functionalinteractionsbetween pages 5-6).

Expert opinions and authoritative analyses
• Foundational and integrative studies from leading groups (Blacque, Leroux, Reiter, Barr) define the TZ as a modular gate with MKS and NPHP modules, where B9 proteins (including MKSR‑2) form a core unit that stabilizes other MKS components and supports barrier function. The cooperative, parallel action of these modules is supported by conserved genetic interactions and localization hierarchies (Bialas et al., 2009; Jensen et al., 2015; Li et al., 2016; Yee et al., 2015; URLs above) (bialas2009functionalinteractionsbetween pages 5-6, lange2021interpretingthepathogenicity pages 17-20, bialas2009functionalinteractionsbetween pages 1-2).

Human disease links (Joubert syndrome and related ciliopathies)
• Genetic association: Human B9D2/MKSR2 is implicated in JBTS. C. elegans modeling of patient missense variants (P74S, G155S) demonstrates pathogenicity with perturbed TZ organization, altered recruitment of MKS‑2/TMEM216, and barrier defects (Lange et al., 2021; DMM; https://doi.org/10.1101/2020.05.22.110668) (lange2021interpretingthepathogenicity pages 14-17).
• Broader MKS-module context: Multiple TMEM proteins at the TZ (including TMEM237/JBTS‑14) are linked to JBTS and require B9/MKS factors for proper function; B9D1/B9D2 requirements are documented in C. elegans models and human genetics (Huang et al., 2011; AJHG; https://doi.org/10.1016/j.ajhg.2011.11.005) (bialas2009functionalinteractionsbetween pages 1-2).

Limitations and open questions
• Biochemical mechanisms by which the B9 domain of MKSR-2 contributes to membrane association or scaffolding at the TZ remain incompletely understood. Quantitative stoichiometry and direct physical interaction maps with MKS‑2/TMEM216 and other TMEMs are active areas for refinement. Nevertheless, hierarchical genetic and localization data firmly position MKSR‑2 as a core structural organizer within the MKS module (Lange et al., 2021; Li et al., 2016) (lange2021interpretingthepathogenicity pages 14-17, bialas2009functionalinteractionsbetween pages 1-2).

Relevant statistics and data points
• TZ composition changes in patient alleles: G155S reduces MKS‑2/TMEM216 at the TZ by ~50–75% and decreases JBTS‑14/TMEM237 and MKS‑6/CC2D2A by ~20% relative to wild type; P74S exhibits milder reductions (Lange et al., 2021; DMM; https://doi.org/10.1101/2020.05.22.110668) (lange2021interpretingthepathogenicity pages 17-20, lange2021interpretingthepathogenicity pages 14-17).
• Barrier defects: RPI‑2 (periciliary RP2 homologue) mislocalizes into cilia in mksr‑2 null and G155S, indicating TZ gate disruption; P74S does not cause RPI‑2 leakage (Lange et al., 2021; DMM; https://doi.org/10.1101/2020.05.22.110668) (lange2021interpretingthepathogenicity pages 14-17).
• Single vs. combined mutants: Single mksr‑2 mutants show modest phenotypic effects in standard assays; combinations with nphp‑1/nphp‑4 or other MKS genes produce strong ciliogenesis and structural phenotypes, reflecting module redundancy and parallelism (Bialas et al., 2009; J Cell Sci; https://doi.org/10.1242/jcs.028621; Yee et al., 2015; PLoS Genet; https://doi.org/10.1371/journal.pgen.1005627) (bialas2009functionalinteractionsbetween pages 9-10, bialas2009functionalinteractionsbetween pages 1-2).

Embedded summary table
| Aspect | Key finding (1–2 sentences) | Principal source(s) with year | URL(s) |
|---|---|---:|---|
| Verification | mksr-2 (C. elegans gene Y38F2AL.2) encodes a B9 domain–containing protein (B9D2) consistent with UniProt Q9N423 and the B9/C2_B9 domain signature. | Bialas et al., 2009 (J Cell Sci) (bialas2009functionalinteractionsbetween pages 5-6) | https://doi.org/10.1242/jcs.028621 |
| Localization | MKSR‑2 localizes to ciliary transition zones / basal bodies in C. elegans sensory neurons, with conserved basal-body/centrosome localization observed in mammalian cells. | Bialas et al., 2009 (bialas2009functionalinteractionsbetween pages 5-6, bialas2009functionalinteractionsbetween pages 1-2) | https://doi.org/10.1242/jcs.028621 |
| Complex membership | MKSR‑2 is a core member of the B9/MKS module, forming a three‑member B9 complex with MKS‑1 and MKSR‑1 (B9D1) required for proper TZ localization. | Bialas et al., 2009; related summaries (bialas2009functionalinteractionsbetween pages 9-10, bialas2009functionalinteractionsbetween pages 1-2) | https://doi.org/10.1242/jcs.028621 |
| Key interactions | MKSR‑2 is necessary for TZ recruitment/stability of MKS‑2/TMEM216 and peripheral MKS proteins (e.g., JBTS‑14/TMEM237, MKS‑6/CC2D2A) but is not required for CEP‑290 or MKS‑5 (RPGRIP1L) TZ localization. | Lange et al., 2021 (lange2021interpretingthepathogenicity pages 17-20, lange2021interpretingthepathogenicity pages 14-17) | https://doi.org/10.1101/2020.05.22.110668; https://doi.org/10.1371/journal.pbio.1002416 |
| Genetic interactions | MKSR‑2 genetically interacts with NPHP‑module genes (e.g., nphp‑4); combined loss (MKS + NPHP) produces severe TZ ultrastructure and ciliogenesis defects, revealing module redundancy. | Bialas 2009; Lange 2021; Yee 2015 (bialas2009functionalinteractionsbetween pages 9-10, lange2021interpretingthepathogenicity pages 14-17) | https://doi.org/10.1242/jcs.028621; https://doi.org/10.1101/2020.05.22.110668; https://doi.org/10.1371/journal.pgen.1005627 |
| Phenotypes | mksr‑2 null and patient‑derived missense alleles (P74S, G155S) cause shortened/mispositioned cilia, loss of TZ Y‑links, TZ gating defects (e.g., RPI‑2 leakage), and sensory/behavioral deficits; G155S shows stronger effects. | Lange et al., 2021 (lange2021interpretingthepathogenicity pages 14-17) | https://doi.org/10.1101/2020.05.22.110668 |
| Human disease links | Human B9D2/MKSR2 is linked to Joubert syndrome; patient missense variants modeled in C. elegans are pathogenic and recapitulate TZ and ciliary defects. | Lange 2021; Huang et al., 2011 (lange2021interpretingthepathogenicity pages 14-17) | https://doi.org/10.1101/2020.05.22.110668; https://doi.org/10.1016/j.ajhg.2011.11.005 |
| 2023–2024 updates (scan) | This literature scan found limited MKSR‑2–specific primary papers in 2023–2024; recent 2023–24 reviews/studies discuss TZ assembly and ciliary machinery broadly but few new MKSR‑2–specific functional studies were identified. | Recent scan / reviews (no major MKSR‑2 primary papers 2023–24 found in this search) (park2019ciliumlengthregulation pages 21-24) | Representative resources: Li et al., 2016 (assembly) https://doi.org/10.1371/journal.pbio.1002416; Rodrigues 2024 (dynein‑2 review) |

Table: Concise, cited summary of MKSR‑2 (B9D2) in C. elegans covering identity, localization, module membership, interactions, genetic/phenotypic evidence, and limited 2023–24 updates; useful as a quick reference of principal findings and sources.

Conclusion
Collectively, C. elegans mksr‑2 encodes a TZ-localized B9D2 protein that operates as a core organizer within the MKS module to establish and maintain the ciliary diffusion barrier and to scaffold recruitment of other MKS/TMEM factors. Its function is downstream of master TZ scaffolds (MKS‑5/RPGRIP1L, CEP‑290) and cooperates in parallel with NPHP-module proteins to support ciliogenesis and ciliary signaling. Patient-mimicking missense alleles in worms corroborate B9D2’s role in JBTS pathogenesis by quantifiably altering TZ composition and gate function (Bialas 2009; Jensen 2015; Li 2016; Yee 2015; Lange 2021; URLs and dates above) (bialas2009functionalinteractionsbetween pages 5-6, lange2021interpretingthepathogenicity pages 17-20, bialas2009functionalinteractionsbetween pages 1-2, lange2021interpretingthepathogenicity pages 14-17).

References

1. (bialas2009functionalinteractionsbetween pages 5-6): Nathan J. Bialas, Peter N. Inglis, Chunmei Li, Jon F. Robinson, Jeremy D. K. Parker, Michael P. Healey, Erica E. Davis, Chrystal D. Inglis, Tiina Toivonen, David C. Cottell, Oliver E. Blacque, Lynne M. Quarmby, Nicholas Katsanis, and Michel R. Leroux. Functional interactions between the ciliopathy-associated meckel syndrome 1 (mks1) protein and two novel mks1-related (mksr) proteins. Journal of Cell Science, 122:611-624, Mar 2009. URL: https://doi.org/10.1242/jcs.028621, doi:10.1242/jcs.028621. This article has 96 citations and is from a domain leading peer-reviewed journal.

2. (bialas2009functionalinteractionsbetween pages 1-2): Nathan J. Bialas, Peter N. Inglis, Chunmei Li, Jon F. Robinson, Jeremy D. K. Parker, Michael P. Healey, Erica E. Davis, Chrystal D. Inglis, Tiina Toivonen, David C. Cottell, Oliver E. Blacque, Lynne M. Quarmby, Nicholas Katsanis, and Michel R. Leroux. Functional interactions between the ciliopathy-associated meckel syndrome 1 (mks1) protein and two novel mks1-related (mksr) proteins. Journal of Cell Science, 122:611-624, Mar 2009. URL: https://doi.org/10.1242/jcs.028621, doi:10.1242/jcs.028621. This article has 96 citations and is from a domain leading peer-reviewed journal.

3. (lange2021interpretingthepathogenicity pages 17-20): Karen I. Lange, Sofia Tsiropoulou, Katarzyna Kucharska, and Oliver E. Blacque. Interpreting the pathogenicity of joubert syndrome missense variants in caenorhabditis elegans. Disease Models & Mechanisms, May 2021. URL: https://doi.org/10.1101/2020.05.22.110668, doi:10.1101/2020.05.22.110668. This article has 26 citations and is from a domain leading peer-reviewed journal.

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6. (park2019ciliumlengthregulation pages 21-24): K Park. Cilium length regulation in caenorhabditis elegans. Unknown journal, 2019.

Citations

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2. lange2021interpretingthepathogenicity pages 14-17
3. lange2021interpretingthepathogenicity pages 17-20
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