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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: Q09459
• Protein Description: RecName: Full=Protein fantom; AltName: Full=Meckel syndrome protein homolog; Flags: Precursor;
• Gene Information: Name=mks-5; Synonyms=ftm, nphp-8; ORFNames=C09G5.8;
• Organism (full): Caenorhabditis elegans.
• Protein Family: Belongs to the RPGRIP1 family. .
• Key Domains: C2-C2_1. (IPR021656); C2_domain_sf. (IPR035892); RPGRIP1_fam. (IPR031139); C2-C2_1 (PF11618)

MANDATORY VERIFICATION STEPS:

1. Check if the gene symbol "mks-5" 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 'mks-5' 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 mks-5 (gene ID: mks-5, UniProt: Q09459) 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this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.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: Q09459
• Protein Description: RecName: Full=Protein fantom; AltName: Full=Meckel syndrome protein homolog; Flags: Precursor;
• Gene Information: Name=mks-5; Synonyms=ftm, nphp-8; ORFNames=C09G5.8;
• Organism (full): Caenorhabditis elegans.
• Protein Family: Belongs to the RPGRIP1 family. .
• Key Domains: C2-C2_1. (IPR021656); C2_domain_sf. (IPR035892); RPGRIP1_fam. (IPR031139); C2-C2_1 (PF11618)

MANDATORY VERIFICATION STEPS:

1. Check if the gene symbol "mks-5" 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 'mks-5' 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 mks-5 (gene ID: mks-5, UniProt: Q09459) 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 status (abbreviated): Identity verified (C. elegans mks-5 = RPGRIP1L ortholog with C2 and coiled-coil domains); foundational and recent literature collected (2015–2016 primary worm studies; 2024 diagnostic-imaging review); targeted evidence extracted (localization, domain dependencies, scaffolding hierarchy, gating/PIP2, phenotypes); artifact created (key-facts table). The report below integrates these findings with citations and URLs.

Comprehensive research report: C. elegans mks-5 (UniProt Q09459)

Verification of identity and scope
- Gene/protein identity: mks-5 in Caenorhabditis elegans encodes the Meckel syndrome protein homolog and is the ortholog of mammalian RPGRIP1L/RPGRIP1, a member of the RPGRIP1 family. It contains coiled-coil and C2 domains and functions at the ciliary transition zone (TZ) (The EMBO Journal, 2015; DOI: 10.15252/embj.201488044; published Oct 2015; https://doi.org/10.15252/embj.201488044) (jensen2015formationofthe pages 1-2). Foundational worm genetics and cell biology further corroborate this orthology and role (PLOS Biology, 2016; DOI: 10.1371/journal.pbio.1002416; published Mar 2016; https://doi.org/10.1371/journal.pbio.1002416) (li2016mks5andcep290 pages 2-3).

1) Key concepts and current definitions
- Transition zone (TZ) and ciliary gate: The TZ is a membrane-cytoskeleton specialization immediately distal to transition fibers that establishes a selective diffusion barrier (“ciliary gate”) and prominent Y-link ultrastructures connecting axonemal microtubules to the ciliary membrane. In C. elegans, MKS-5 is the central assembly factor that builds this TZ and organizes two conserved protein modules (MKS and NPHP) (EMBO J 2015, Oct 2015; https://doi.org/10.15252/embj.201488044) (jensen2015formationofthe pages 1-2, jensen2015formationofthe pages 7-8). The MKS-5-dependent TZ creates a ciliary zone of exclusion (CIZE) to compartmentalize signaling proteins and lipids (EMBO J 2015; https://doi.org/10.15252/embj.201488044) (jensen2015formationofthe pages 12-14, jensen2015formationofthe pages 15-16).
- Modules and hierarchical assembly: Genetic and localization analyses define two TZ assembly branches: an MKS-pathway centered on CEP-290 and an NPHP-pathway centered on NPHP-1/NPHP-4 at transition fibers. MKS-5 acts upstream as the foundational scaffold for both branches (PLOS Biol 2016; Mar 2016; https://doi.org/10.1371/journal.pbio.1002416) (li2016mks5andcep290 pages 2-3, li2016mks5andcep290 pages 3-5, li2016mks5andcep290 pages 16-18).

2) Molecular features, localization, and interaction dependencies
- Domain architecture and requirements: MKS-5 contains coiled-coil and C2 domains. Its coiled-coil region is required for CEP-290 localization to the TZ, and the C2/coiled-coil regions contribute to MKS-5 targeting and function at the TZ (EMBO J 2015; https://doi.org/10.15252/embj.201488044) (jensen2015formationofthe pages 1-2). CEP-290 requires the MKS-5 coiled-coil for proper TZ localization (PLOS Biol 2016; https://doi.org/10.1371/journal.pbio.1002416) (li2016mks5andcep290 pages 9-11).
- Subcellular localization: Endogenous and tagged MKS-5 localizes to the TZ, sometimes appearing as two symmetric foci flanking the compartment, immediately distal to transition fibers (EMBO J 2015; https://doi.org/10.15252/embj.201488044) (jensen2015formationofthe pages 12-14, jensen2015formationofthe pages 7-8).
- Scaffold role and module organization: MKS-5 is necessary for the TZ localization of essentially all known TZ proteins in C. elegans and is required to establish TZ ultrastructure. It organizes both the MKS module (including core components MKSR-1, MKSR-2/MKS-2, TMEM-231, TMEM-17) and the NPHP module (NPHP-1/NPHP-4) (EMBO J 2015; https://doi.org/10.15252/embj.201488044) (jensen2015formationofthe pages 7-8, jensen2015formationofthe pages 15-16). CEP-290 acts as a core assembly factor for the MKS pathway; its loss abrogates localization of MKS-pathway proteins (e.g., TMEM-218, TMEM-231, MKS-2) while NPHP-1/NPHP-4 retain proximal association (PLOS Biol 2016; https://doi.org/10.1371/journal.pbio.1002416) (li2016mks5andcep290 pages 14-16, li2016mks5andcep290 pages 9-11, li2016mks5andcep290 pages 2-3).

3) Role in gating, lipid compartmentalization, and transport
- Ciliary zone of exclusion and lipid gating: The MKS-5-built TZ establishes a CIZE that restricts protein and lipid diffusion. In wild type, a PI(4,5)P2 reporter (PLCd1-PH) is enriched at the periciliary membrane compartment (PCMC) and decays across the TZ, whereas loss of MKS-5 causes PIP2 to leak into the cilium, and PCMC proteins (e.g., TRAM-1) invade cilia (EMBO J 2015; Oct 2015; https://doi.org/10.15252/embj.201488044) (jensen2015formationofthe pages 12-14, jensen2015formationofthe pages 15-16). ARL-13 normally does not cross the TZ but diffuses when TZ ultrastructure is absent (jensen2015formationofthe pages 12-14). MKS-5-dependent TZ integrity also correlates with reduced IFT particle velocity across the TZ, consistent with a structural barrier to trafficking (jensen2015formationofthe pages 15-16).

4) Assembly hierarchy with CEP-290 and specific interactors
- CEP-290 and hierarchical dependencies: Genetic epistasis and localization mapping place MKS-5 upstream of CEP-290; CEP-290 depends on the MKS-5 coiled-coil to localize, and CEP-290 in turn is required for recruiting/retaining MKS core components (e.g., MKS-2, TMEM-231, TMEM-218) and CEP-290–associated proteins (e.g., TMEM-138, CDKL-1) to the TZ. NPHP-1/-4 can assemble at transition fibers and partially at the TZ independently of CEP-290, indicating two assembly arms orchestrated by MKS-5 (PLOS Biol 2016; Mar 2016; https://doi.org/10.1371/journal.pbio.1002416) (li2016mks5andcep290 pages 14-16, li2016mks5andcep290 pages 9-11, li2016mks5andcep290 pages 3-5, li2016mks5andcep290 pages 16-18, li2016mks5andcep290 pages 5-7).

5) Phenotypes and functional consequences in C. elegans sensory neurons
- Ultrastructure and ciliogenesis: mks-5 null mutants lack identifiable TZ ultrastructure, including Y-links, and display disrupted anchoring of the basal body/TZ to the ciliary membrane; in severe combined module mutants (MKS+NPHP) this can lead to complete loss of membrane attachment and axonemal defects (EMBO J 2015; https://doi.org/10.15252/embj.201488044) (jensen2015formationofthe pages 7-8). While single-module mutations can leave overall ciliogenesis partly intact, double defects are synthetic and severe (PLOS Biol 2016; https://doi.org/10.1371/journal.pbio.1002416) (li2016mks5andcep290 pages 2-3).
- Signaling and trafficking: Loss of MKS-5 disrupts compartmentalization, allowing GPCRs and ARL-13 to mislocalize, and alters lipid composition (PIP2 accumulation in cilia). IFT dynamics across the TZ are perturbed (reduced velocity) when the TZ is compromised (EMBO J 2015; https://doi.org/10.15252/embj.201488044) (jensen2015formationofthe pages 15-16). Dye-filling assays and localization of reporters (e.g., TMEM-218::GFP, MKSR-2::tdTomato) provide sensitive readouts of TZ integrity and genetic interactions; for example, tmem-218 single mutants are mild, but tmem-218;nphp-4 double mutants show pronounced dye-filling defects, supporting a synthetic MKS–NPHP functional relationship (PLOS Biol 2016; https://doi.org/10.1371/journal.pbio.1002416) (li2016mks5andcep290 pages 5-7).

6) Relevance to human ciliopathies and 2023–2024 developments
- Disease links: The RPGRIP1L ortholog (MKS-5) is central to a conserved TZ program; disruption of RPGRIP1L or interacting TZ components causes human ciliopathies, including Meckel and Joubert syndromes. Super-resolution imaging of patient fibroblasts with RPGRIP1L or TCTN2 mutations demonstrates loss or displacement of MKS/NPHP complexes from the TZ and impaired Hedgehog signaling (e.g., reduced ciliary SMO recruitment), underscoring diagnostic/functional relevance (Laser & Optoelectronics Progress, 2024; DOI: 10.3788/lop232684; published Jan 2024; https://doi.org/10.3788/lop232684) (zhen2024superresolutionfluorescencemicroscopy pages 5-8). Foundational worm studies connect TZ disassembly to lipid/signaling defects and suggest that correct TZ architecture is necessary to maintain ciliary phosphoinositide composition (EMBO J 2015; https://doi.org/10.15252/embj.201488044) (jensen2015formationofthe pages 15-16, jensen2015formationofthe pages 12-14).
- Gene discovery and clinical genetics context: The CEP-290–dependent MKS-pathway defined in C. elegans helped identify OFD6/JBTS-related variants in TZ membrane proteins (TMEM17, TMEM138, TMEM231) in human families; patient fibroblasts with TMEM17 mutation show markedly reduced ciliogenesis (PLOS Biol 2016; https://doi.org/10.1371/journal.pbio.1002416) (li2016mks5andcep290 pages 3-5, li2016mks5andcep290 pages 12-14). These cross-species links motivate functional annotation strategies in worm to inform variant interpretation in the clinic.

7) Current applications and implementations
- Diagnostic imaging: Super-resolution microscopy (STORM/3D-SIM) reveals TZ architectural losses in patient cells with RPGRIP1L mutations and provides a “molecular fingerprint” approach for ciliopathy diagnosis by mapping TZ protein rings and their displacement (2024 invited review; https://doi.org/10.3788/lop232684) (zhen2024superresolutionfluorescencemicroscopy pages 5-8). Correlative imaging (STORM–TEM) and ciliary signaling assays (SMO translocation after SAG stimulation) are used as functional diagnostics in research and translational settings (zhen2024superresolutionfluorescencemicroscopy pages 5-8).
- Experimental readouts in models: In C. elegans, PIP2 reporters (PLCd1-PH-GFP), ARL-13/GPCR localization, IFT particle tracking, and dye-filling provide quantitative and qualitative metrics of TZ function that can be used to assay variant effects and to screen for modifiers (EMBO J 2015; https://doi.org/10.15252/embj.201488044) (jensen2015formationofthe pages 12-12, jensen2015formationofthe pages 15-16). These readouts are directly translatable to mammalian cells (e.g., SMO assays, ARL13B localization) in clinical research pipelines (zhen2024superresolutionfluorescencemicroscopy pages 5-8).

8) Expert perspectives and analysis
- Conceptual model: MKS-5/RPGRIP1L is best described as an upstream scaffold/assembly factor that positions and stabilizes the TZ, bridging the MKS and NPHP modules. CEP-290 is the core structural factor for the MKS branch, essential to assemble core MKS proteins and to build Y-link ultrastructure, while NPHP proteins at transition fibers define the proximal border and contribute to basal body anchoring. This framework explains why single-module mutations can be partially tolerated for ciliogenesis, whereas combined insults cause severe structural and gating failures (PLOS Biol 2016; EMBO J 2015; https://doi.org/10.1371/journal.pbio.1002416; https://doi.org/10.15252/embj.201488044) (li2016mks5andcep290 pages 16-18, li2016mks5andcep290 pages 2-3, jensen2015formationofthe pages 7-8). The accompanying lipid-gating role (PIP2 exclusion) links TZ architecture to cargo sorting pathways (e.g., INPP5E/TULP3 routes), offering a mechanistic bridge to signaling phenotypes observed in patient cells (EMBO J 2015; https://doi.org/10.15252/embj.201488044; 2024 review; https://doi.org/10.3788/lop232684) (jensen2015formationofthe pages 15-16, zhen2024superresolutionfluorescencemicroscopy pages 5-8).

9) Relevant statistics and data
- Structural: Complete loss of mks-5 or cep-290 eliminates TZ Y-link ultrastructure in C. elegans by TEM, while some transition fiber-associated NPHP proteins persist proximally (PLOS Biol 2016; https://doi.org/10.1371/journal.pbio.1002416) (li2016mks5andcep290 pages 14-16). In mks-5 mutants, EM and fluorescence analyses document TZ absence/loosening and basal body detachment from the membrane in severe genetic combinations (EMBO J 2015; https://doi.org/10.15252/embj.201488044) (jensen2015formationofthe pages 7-8).
- Molecular readouts: PIP2 reporter signal, normally decaying across the TZ, spreads into cilia upon mks-5 loss; ARL-13 and PCMC markers breach the gate (EMBO J 2015; https://doi.org/10.15252/embj.201488044) (jensen2015formationofthe pages 12-14). IFT velocity is reduced within the compromised TZ, consistent with a physical barrier remodeling (jensen2015formationofthe pages 15-16). These experimental metrics provide quantitative handles for functional annotation.

Embedded summary table of key facts
| Aspect | Finding / Description | Experimental evidence / readout | Dependencies / Hierarchy | Key citation (DOI URL, year) |
|---|---|---|---|---|
| Identity / organism / family | mks-5 is the Caenorhabditis elegans orthologue of RPGRIP1L (Meckel syndrome protein homolog); UniProt Q09459; member of RPGRIP1 family | Sequence annotation and genetic orthology assignments; functional studies in C. elegans | Orthologous to mammalian RPGRIP1L/RPGRIP1; conserved TZ role across species | Jensen et al., EMBO J 2015, https://doi.org/10.15252/embj.201488044 (jensen2015formationofthe pages 1-2); Li et al., PLoS Biol 2016, https://doi.org/10.1371/journal.pbio.1002416 (li2016mks5andcep290 pages 2-3) |
| Subcellular localization | Localises to the ciliary transition zone (TZ), often as proximal foci immediately distal to transition fibres | Fluorescent protein fusions (GFP/tdTomato), immunofluorescence; TEM showing Y-links at TZ | Localizes to TZ independently of some downstream MKS proteins but is required to position other TZ components | Jensen et al., EMBO J 2015, https://doi.org/10.15252/embj.201488044 (jensen2015formationofthe pages 1-2, jensen2015formationofthe pages 12-14) |
| Domain requirements (coiled-coil, C2) | Coiled-coil region required for CEP-290 localisation; C2 domains (N/C) and coiled-coils required for TZ targeting and function | Domain-truncation constructs and localisation assays (rescue/mislocalisation of reporters) | Specific MKS-5 domains mediate interactions with CEP-290 and other TZ modules | Jensen et al., EMBO J 2015, https://doi.org/10.15252/embj.201488044 (jensen2015formationofthe pages 1-2); Li et al., PLoS Biol 2016, https://doi.org/10.1371/journal.pbio.1002416 (li2016mks5andcep290 pages 9-11) |
| Scaffold / assembly factor function | Acts as a central assembly scaffold/assembly factor that nucleates TZ formation and organizes both MKS and NPHP modules | Genetic dependency mapping, colocalisation assays, rescue experiments, TEM ultrastructure analysis | Upstream foundation: MKS-5 is required to recruit/retain many TZ proteins from both MKS and NPHP modules | Li et al., PLoS Biol 2016, https://doi.org/10.1371/journal.pbio.1002416 (li2016mks5andcep290 pages 2-3, li2016mks5andcep290 pages 3-5) |
| CEP-290 dependency & assembly hierarchy | MKS-5 sits upstream; CEP-290 is core to the MKS-module assembly pathway and requires MKS-5 coiled-coil for localisation; CEP-290 is required to recruit core MKS proteins (e.g., MKS-2, TMEM-231, TMEM-218) | Loss-of-function and localisation studies showing CEP-290-dependent vs CEP-290-independent components; genetic epistasis | Hierarchy: MKS-5 (foundation) → CEP-290 (MKS-pathway core) → core MKS proteins; NPHP module can assemble partly independently | Li et al., PLoS Biol 2016, https://doi.org/10.1371/journal.pbio.1002416 (li2016mks5andcep290 pages 14-16, li2016mks5andcep290 pages 9-11) |
| Ciliary gate / CIZE and PIP2 regulation | MKS-5 establishes a ciliary zone of exclusion (CIZE) at the TZ that helps exclude PI(4,5)P2 from the cilium, maintaining distinct lipid/signalling compartments | PLCd1-PH (PIP2) reporters, TRAM-1 and ARL-13 localisation probes, lipid reporter imaging showing PIP2 leakage in mks-5 mutants | Gate function depends on intact TZ assembly (MKS-5 + CEP-290 and MKS components) | Jensen et al., EMBO J 2015, https://doi.org/10.15252/embj.201488044 (jensen2015formationofthe pages 12-14, jensen2015formationofthe pages 15-16) |
| Phenotypes in C. elegans sensory neurons | mks-5 loss (and combined MKS+NPHP defects) produces loss of TZ ultrastructure (Y-links), basal body/TZ membrane detachment, dye-filling defects, mislocalisation of ciliary GPCRs/ARL-13, and synthetic ciliogenesis defects | TEM (Y-link loss), DiI dye-filling assays, fluorescent reporter mislocalisation, genetic synthetic interaction assays | Severity increases in combined MKS+NPHP mutants (synthetic phenotypes); individual modules can show partial redundancy | Jensen et al., EMBO J 2015, https://doi.org/10.15252/embj.201488044 (jensen2015formationofthe pages 7-8, jensen2015formationofthe pages 15-16); Li et al., PLoS Biol 2016, https://doi.org/10.1371/journal.pbio.1002416 (li2016mks5andcep290 pages 5-7) |
| Effects on IFT and protein diffusion | TZ defects reduce IFT velocity across the TZ and compromise the diffusion barrier (e.g., ARL-13 and other proteins leak or fail to be retained) | IFT particle tracking, velocity measurements, FRAP/diffusion assays, localisation of ARL-13 and GPCR reporters | Barrier/IFT effects correlate with structural TZ loss driven by MKS-5/CEP-290 disruption | Jensen et al., EMBO J 2015, https://doi.org/10.15252/embj.201488044 (jensen2015formationofthe pages 15-16) |
| Human ciliopathy links & diagnostic imaging | Mammalian RPGRIP1L mutations linked to Joubert/Meckel-like ciliopathies; super-resolution (STORM/3D-SIM) and correlative imaging reveal loss/displacement of TZ MKS/NPHP complexes in patient cells and impaired Hh signalling (e.g., reduced SMO recruitment) | Patient fibroblast imaging (3D-SIM/STORM), SMO/Arl13 assays after SAG stimulation, correlative TEM | Conservation of TZ assembly/function supports C. elegans mks-5 as a model to study RPGRIP1L-related disease mechanisms | Li et al., PLoS Biol 2016, https://doi.org/10.1371/journal.pbio.1002416 (li2016mks5andcep290 pages 3-5); Zhen & Yang, Laser & Optoelectronics Progress 2024, https://doi.org/10.3788/lop232684 (zhen2024superresolutionfluorescencemicroscopy pages 5-8) |
| Diagnostic / experimental readouts used | Common readouts: TEM (Y-links), DiI dye-filling, PIP2 reporters (PLCd1-PH-GFP), ARL-13/GPCR localisation, IFT velocity tracking, super-resolution STORM/3D-SIM for TZ architecture | Combined EM, confocal/super-resolution, live IFT imaging, genetic epistasis and rescue assays | These assays link molecular defects (domain mutations, mislocalisation) to ultrastructural and signalling phenotypes useful for translational/diagnostic studies | Jensen et al., EMBO J 2015, https://doi.org/10.15252/embj.201488044 (jensen2015formationofthe pages 12-12); Zhen & Yang 2024, https://doi.org/10.3788/lop232684 (zhen2024superresolutionfluorescencemicroscopy pages 5-8) |

Table: Concise summary table of C. elegans mks-5 (RPGRIP1L ortholog) covering identity, localization, domain requirements, scaffold/assembly roles, CEP-290 hierarchy, gating/PIP2 regulation, phenotypes, human disease links, and principal assays; entries cite primary C. elegans studies and recent imaging context for diagnostics.

Conclusions
C. elegans mks-5 (UniProt Q09459) encodes the RPGRIP1L ortholog and acts as a central scaffold to assemble the ciliary transition zone, using coiled-coil and C2 domains to localize and to organize MKS and NPHP modules. It establishes a diffusion barrier (CIZE) that compartmentalizes proteins and lipids, including exclusion of PIP2, and coordinates IFT transit. Genetic and localization hierarchies place MKS-5 upstream of CEP-290, which is essential to recruit core MKS components and to form Y-link ultrastructure. Loss of mks-5 disrupts TZ structure, gating, and signaling in C. elegans sensory neurons, and ortholog defects in humans (RPGRIP1L) underpin ciliopathies detectable by super-resolution diagnostic imaging. These mechanistic insights provide precise, evidence-based functional annotation and a translational bridge from worm genetics to human disease (EMBO J 2015; PLOS Biol 2016; Laser & Optoelectronics Progress 2024) (jensen2015formationofthe pages 15-16, li2016mks5andcep290 pages 14-16, zhen2024superresolutionfluorescencemicroscopy pages 5-8).

References

1. (jensen2015formationofthe pages 1-2): Victor L Jensen, Chunmei Li, Rachel V Bowie, Lara Clarke, Swetha Mohan, Oliver E Blacque, and Michel R Leroux. Formation of the transition zone by mks5/rpgrip1l establishes a ciliary zone of exclusion (cize) that compartmentalises ciliary signalling proteins and controls pip2 ciliary abundance. The EMBO Journal, 34:2537-2556, Oct 2015. URL: https://doi.org/10.15252/embj.201488044, doi:10.15252/embj.201488044. This article has 159 citations.

2. (li2016mks5andcep290 pages 2-3): Chunmei Li, Victor L. Jensen, Kwangjin Park, Julie Kennedy, Francesc R. Garcia-Gonzalo, Marta Romani, Roberta De Mori, Ange-Line Bruel, Dominique Gaillard, Bérénice Doray, Estelle Lopez, Jean-Baptiste Rivière, Laurence Faivre, Christel Thauvin-Robinet, Jeremy F. Reiter, Oliver E. Blacque, Enza Maria Valente, and Michel R. Leroux. Mks5 and cep290 dependent assembly pathway of the ciliary transition zone. PLOS Biology, 14:e1002416, Mar 2016. URL: https://doi.org/10.1371/journal.pbio.1002416, doi:10.1371/journal.pbio.1002416. This article has 165 citations and is from a highest quality peer-reviewed journal.

3. (jensen2015formationofthe pages 7-8): Victor L Jensen, Chunmei Li, Rachel V Bowie, Lara Clarke, Swetha Mohan, Oliver E Blacque, and Michel R Leroux. Formation of the transition zone by mks5/rpgrip1l establishes a ciliary zone of exclusion (cize) that compartmentalises ciliary signalling proteins and controls pip2 ciliary abundance. The EMBO Journal, 34:2537-2556, Oct 2015. URL: https://doi.org/10.15252/embj.201488044, doi:10.15252/embj.201488044. This article has 159 citations.

4. (jensen2015formationofthe pages 12-14): Victor L Jensen, Chunmei Li, Rachel V Bowie, Lara Clarke, Swetha Mohan, Oliver E Blacque, and Michel R Leroux. Formation of the transition zone by mks5/rpgrip1l establishes a ciliary zone of exclusion (cize) that compartmentalises ciliary signalling proteins and controls pip2 ciliary abundance. The EMBO Journal, 34:2537-2556, Oct 2015. URL: https://doi.org/10.15252/embj.201488044, doi:10.15252/embj.201488044. This article has 159 citations.

5. (jensen2015formationofthe pages 15-16): Victor L Jensen, Chunmei Li, Rachel V Bowie, Lara Clarke, Swetha Mohan, Oliver E Blacque, and Michel R Leroux. Formation of the transition zone by mks5/rpgrip1l establishes a ciliary zone of exclusion (cize) that compartmentalises ciliary signalling proteins and controls pip2 ciliary abundance. The EMBO Journal, 34:2537-2556, Oct 2015. URL: https://doi.org/10.15252/embj.201488044, doi:10.15252/embj.201488044. This article has 159 citations.

6. (li2016mks5andcep290 pages 3-5): Chunmei Li, Victor L. Jensen, Kwangjin Park, Julie Kennedy, Francesc R. Garcia-Gonzalo, Marta Romani, Roberta De Mori, Ange-Line Bruel, Dominique Gaillard, Bérénice Doray, Estelle Lopez, Jean-Baptiste Rivière, Laurence Faivre, Christel Thauvin-Robinet, Jeremy F. Reiter, Oliver E. Blacque, Enza Maria Valente, and Michel R. Leroux. Mks5 and cep290 dependent assembly pathway of the ciliary transition zone. PLOS Biology, 14:e1002416, Mar 2016. URL: https://doi.org/10.1371/journal.pbio.1002416, doi:10.1371/journal.pbio.1002416. This article has 165 citations and is from a highest quality peer-reviewed journal.

7. (li2016mks5andcep290 pages 16-18): Chunmei Li, Victor L. Jensen, Kwangjin Park, Julie Kennedy, Francesc R. Garcia-Gonzalo, Marta Romani, Roberta De Mori, Ange-Line Bruel, Dominique Gaillard, Bérénice Doray, Estelle Lopez, Jean-Baptiste Rivière, Laurence Faivre, Christel Thauvin-Robinet, Jeremy F. Reiter, Oliver E. Blacque, Enza Maria Valente, and Michel R. Leroux. Mks5 and cep290 dependent assembly pathway of the ciliary transition zone. PLOS Biology, 14:e1002416, Mar 2016. URL: https://doi.org/10.1371/journal.pbio.1002416, doi:10.1371/journal.pbio.1002416. This article has 165 citations and is from a highest quality peer-reviewed journal.

8. (li2016mks5andcep290 pages 9-11): Chunmei Li, Victor L. Jensen, Kwangjin Park, Julie Kennedy, Francesc R. Garcia-Gonzalo, Marta Romani, Roberta De Mori, Ange-Line Bruel, Dominique Gaillard, Bérénice Doray, Estelle Lopez, Jean-Baptiste Rivière, Laurence Faivre, Christel Thauvin-Robinet, Jeremy F. Reiter, Oliver E. Blacque, Enza Maria Valente, and Michel R. Leroux. Mks5 and cep290 dependent assembly pathway of the ciliary transition zone. PLOS Biology, 14:e1002416, Mar 2016. URL: https://doi.org/10.1371/journal.pbio.1002416, doi:10.1371/journal.pbio.1002416. This article has 165 citations and is from a highest quality peer-reviewed journal.

9. (li2016mks5andcep290 pages 14-16): Chunmei Li, Victor L. Jensen, Kwangjin Park, Julie Kennedy, Francesc R. Garcia-Gonzalo, Marta Romani, Roberta De Mori, Ange-Line Bruel, Dominique Gaillard, Bérénice Doray, Estelle Lopez, Jean-Baptiste Rivière, Laurence Faivre, Christel Thauvin-Robinet, Jeremy F. Reiter, Oliver E. Blacque, Enza Maria Valente, and Michel R. Leroux. Mks5 and cep290 dependent assembly pathway of the ciliary transition zone. PLOS Biology, 14:e1002416, Mar 2016. URL: https://doi.org/10.1371/journal.pbio.1002416, doi:10.1371/journal.pbio.1002416. This article has 165 citations and is from a highest quality peer-reviewed journal.

10. (li2016mks5andcep290 pages 5-7): Chunmei Li, Victor L. Jensen, Kwangjin Park, Julie Kennedy, Francesc R. Garcia-Gonzalo, Marta Romani, Roberta De Mori, Ange-Line Bruel, Dominique Gaillard, Bérénice Doray, Estelle Lopez, Jean-Baptiste Rivière, Laurence Faivre, Christel Thauvin-Robinet, Jeremy F. Reiter, Oliver E. Blacque, Enza Maria Valente, and Michel R. Leroux. Mks5 and cep290 dependent assembly pathway of the ciliary transition zone. PLOS Biology, 14:e1002416, Mar 2016. URL: https://doi.org/10.1371/journal.pbio.1002416, doi:10.1371/journal.pbio.1002416. This article has 165 citations and is from a highest quality peer-reviewed journal.

11. (zhen2024superresolutionfluorescencemicroscopy pages 5-8): Liu Zhen and Wu Yang. Super-resolution fluorescence microscopy for cilia investigation and ciliopathy diagnosis (invited). Laser & Optoelectronics Progress, 61:0618016, Jan 2024. URL: https://doi.org/10.3788/lop232684, doi:10.3788/lop232684. This article has 1 citations.

12. (li2016mks5andcep290 pages 12-14): Chunmei Li, Victor L. Jensen, Kwangjin Park, Julie Kennedy, Francesc R. Garcia-Gonzalo, Marta Romani, Roberta De Mori, Ange-Line Bruel, Dominique Gaillard, Bérénice Doray, Estelle Lopez, Jean-Baptiste Rivière, Laurence Faivre, Christel Thauvin-Robinet, Jeremy F. Reiter, Oliver E. Blacque, Enza Maria Valente, and Michel R. Leroux. Mks5 and cep290 dependent assembly pathway of the ciliary transition zone. PLOS Biology, 14:e1002416, Mar 2016. URL: https://doi.org/10.1371/journal.pbio.1002416, doi:10.1371/journal.pbio.1002416. This article has 165 citations and is from a highest quality peer-reviewed journal.

13. (jensen2015formationofthe pages 12-12): Victor L Jensen, Chunmei Li, Rachel V Bowie, Lara Clarke, Swetha Mohan, Oliver E Blacque, and Michel R Leroux. Formation of the transition zone by mks5/rpgrip1l establishes a ciliary zone of exclusion (cize) that compartmentalises ciliary signalling proteins and controls pip2 ciliary abundance. The EMBO Journal, 34:2537-2556, Oct 2015. URL: https://doi.org/10.15252/embj.201488044, doi:10.15252/embj.201488044. This article has 159 citations.

Citations

1. jensen2015formationofthe pages 1-2
2. jensen2015formationofthe pages 12-14
3. jensen2015formationofthe pages 15-16
4. jensen2015formationofthe pages 7-8
5. zhen2024superresolutionfluorescencemicroscopy pages 5-8
6. jensen2015formationofthe pages 12-12
7. https://doi.org/10.15252/embj.201488044
8. https://doi.org/10.1371/journal.pbio.1002416
9. https://doi.org/10.3788/lop232684
10. https://doi.org/10.1371/journal.pbio.1002416;
11. https://doi.org/10.15252/embj.201488044;
12. https://doi.org/10.15252/embj.201488044,
13. https://doi.org/10.1371/journal.pbio.1002416,
14. https://doi.org/10.3788/lop232684,