Affinage

MKS1

Tectonic-like complex member MKS1 · UniProt Q9NXB0

Length
559 aa
Mass
64.5 kDa
Annotated
2026-04-28
41 papers in source corpus 15 papers cited in narrative 15 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

MKS1 is a B9-domain-containing protein essential for primary cilium formation and transition zone (TZ) integrity, functioning as a gatekeeper of ciliary membrane composition and a regulator of Hedgehog and Wnt signaling. MKS1 localizes to the basal body and TZ, where it forms an obligate complex with B9D2 and B9D1 (in the order MKS1–B9D2–B9D1) that establishes a diffusion barrier maintaining distinct ciliary membrane protein composition; the B9 domain is required for this interaction and for TZ targeting (PMID:32726168, PMID:33193692). MKS1 regulates ciliary trafficking of ARL13B and downstream INPP5E to control ciliary phosphoinositide signaling, cooperates with the BBSome and intraflagellar transport machinery for cilium assembly and transmembrane receptor trafficking, and its loss disrupts Hedgehog pathway signaling in neural tube and limb patterning (PMID:28291807, PMID:26490104, PMID:19776033). At the ciliary base, MKS1 interacts with the E2 ubiquitin-conjugating enzyme UBE2E1 to mediate ubiquitination of phosphorylated β-catenin, thereby regulating canonical Wnt signaling, and biallelic loss-of-function mutations in MKS1 cause Meckel–Gruber syndrome and Joubert syndrome (PMID:35170427, PMID:17185389).

Mechanistic history

Synthesis pass · year-by-year structured walk · 8 steps
  1. 2006 High

    The discovery that MKS1 encodes a basal body protein whose knockdown blocks centriole migration and ciliogenesis established MKS1 as a ciliary gene and linked Meckel–Gruber syndrome to defective cilia formation.

    Evidence siRNA knockdown in 3D epithelial cultures, co-immunoprecipitation with meckelin/MKS3, immunofluorescence localization to basal bodies, and comparative genomics/proteomics

    PMID:16415886 PMID:17185389

    Open questions at the time
    • Mechanism by which MKS1 promotes centriole migration was not defined
    • Direct structural role of MKS1 at the basal body versus indirect signaling role was unclear
  2. 2009 High

    In vivo mouse knockout and C. elegans mutant analyses demonstrated that MKS1 is required for ciliogenesis in most tissues and for Hedgehog signal transduction, and revealed co-dependent TZ localization among the B9-domain protein family.

    Evidence Mouse Mks1 KO with neural tube/limb patterning analysis; C. elegans mks-1/mksr-1/mksr-2 GFP localization and genetic epistasis; stable shRNA knockdown in IMCD3 cells

    PMID:19208769 PMID:19515853 PMID:19776033

    Open questions at the time
    • How MKS1 influences Hedgehog component trafficking to cilia was not resolved
    • Whether B9-domain proteins form a direct physical complex or only co-localize was unclear
    • Role of MKS1 in centrosome duplication control was not mechanistically explained
  3. 2010 High

    Mapping the B9-domain deletion showed that mother centriole localization of MKS1 requires its B9 domain and is essential for both motile and non-motile ciliogenesis, planar cell polarity, and Gli3 repressor formation, and genetic epistasis in C. elegans established that MKS and NPHP pathways function in parallel at the TZ.

    Evidence Mouse del64-323 mutant with node flow, neural tube, and limb patterning assays; C. elegans mks/nphp double mutant genetic analysis

    PMID:20150540 PMID:21045211

    Open questions at the time
    • Structural basis of the B9 domain's role in centriole targeting was unknown
    • Direct interaction partners at the mother centriole were not identified
  4. 2011 High

    Proteomic mapping defined MKS1 as the core of a distinct 'MKS module' within the ciliopathy protein network, separate from NPHP modules, and linked this module to IFT-dependent cargo transport.

    Evidence Affinity purification/mass spectrometry, 3D renal culture ciliogenesis assays, and related Co-IP for B9D2–IFT interactions

    PMID:21565611 PMID:21602787

    Open questions at the time
    • Direct binding between MKS1 and IFT particles was not demonstrated
    • Cargo selectivity of the MKS module was not defined
  5. 2015 Medium

    MKS1 was shown to regulate ciliary INPP5E through an ARL13B-dependent mechanism, establishing a signaling hierarchy (MKS1 → ARL13B → INPP5E) that controls ciliary phosphoinositide composition.

    Evidence Immunofluorescence in MKS1-mutant patient fibroblasts and 3D spheroid rescue assays

    PMID:26490104

    Open questions at the time
    • Whether MKS1 directly retains ARL13B or prevents its exit was not distinguished
    • How INPP5E mislocalization contributes to specific MKS phenotypes was not tested
  6. 2017 High

    Genetic epistasis between Mks1, Bbs4, Ift172, and Dync2h1 demonstrated that the MKS TZ complex cooperates with both the BBSome and IFT machinery for ARL13B trafficking and cilium assembly, placing MKS1 at a convergence point for ciliary gating and transport.

    Evidence Double-mutant mouse embryos with ARL13B immunofluorescence and Hedgehog pathway analysis

    PMID:28291807

    Open questions at the time
    • Biochemical basis for MKS1–BBSome cooperation was not defined
    • Whether MKS1 directly contacts IFT components was not tested
  7. 2020 High

    Reconstitution of the B9-domain complex showed that MKS1, B9D2, and B9D1 form an ordered complex (MKS1–B9D2–B9D1) that is required to establish a ciliary membrane diffusion barrier, and that the B9 domain is essential for this interaction and TZ targeting.

    Evidence Co-IP defining interaction order, KO cell lines with rescue, fluorescence recovery diffusion barrier assays, patient-derived fibroblast analysis of B9-domain frameshift mutants

    PMID:32726168 PMID:33193692

    Open questions at the time
    • Structural resolution of the B9 complex is lacking
    • How the B9 complex interfaces with other TZ components (e.g., TCTN, CC2D2A) to form the full barrier was not defined
  8. 2022 High

    Discovery that MKS1 interacts with UBE2E1 at the ciliary base to mediate ubiquitination of phosphorylated β-catenin revealed a non-canonical role for the TZ in regulating canonical Wnt signaling through local ubiquitin processing.

    Evidence Co-IP, co-localization at ciliary base, Mks1 KO mouse, ubiquitination assays, Wnt signaling readouts

    PMID:35170427

    Open questions at the time
    • Whether UBE2E1-mediated ubiquitination of β-catenin is proteasomal or has signaling function was not fully resolved
    • How MKS1-UBE2E1 interaction is regulated (e.g., by phosphorylation or ciliary signals) is unknown
    • Relative contribution of Wnt vs. Hedgehog dysregulation to MKS/JBTS phenotypes is unclear

Open questions

Synthesis pass · forward-looking unresolved questions
  • The structural basis of the B9 complex at the TZ, the mechanism by which MKS1 selectively gates different ciliary membrane cargoes, and the relative contributions of Hedgehog and Wnt pathway disruption to MKS/JBTS organ-specific phenotypes remain unresolved.
  • No high-resolution structure of the MKS1–B9D2–B9D1 complex exists
  • Cargo selectivity rules for the TZ diffusion barrier are unknown
  • How MKS1 loss differentially affects ciliogenesis across tissues is unexplained

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060090 molecular adaptor activity 3
Localization
GO:0005815 microtubule organizing center 3 GO:0005929 cilium 3
Pathway
R-HSA-1852241 Organelle biogenesis and maintenance 5 R-HSA-162582 Signal Transduction 4 R-HSA-1643685 Disease 2
Partners
ARL13BB9D1B9D2BBS4RNF34TMEM67UBE2E1
Complex memberships
MKS/JBTS transition zone moduleMKS1–B9D2–B9D1 (B9 complex)

Evidence

Reading pass · 15 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2006 MKS1 protein localizes to basal bodies in ciliated epithelial cells, while its interaction partner meckelin (MKS3) localizes to the primary cilium and plasma membrane; siRNA-mediated knockdown of Mks1 blocks centriole migration to the apical membrane and prevents primary cilium formation; co-immunoprecipitation demonstrates MKS1 and meckelin interact directly. siRNA knockdown, co-immunoprecipitation, immunofluorescence localization, 3D tissue culture morphogenesis assay Human molecular genetics High 17185389
2006 MKS1 encodes a component of the flagellar apparatus basal body proteome, placing it functionally in ciliary biology; comparative genomics and proteomics implicate MKS1 in ciliary functions. Comparative genomics, proteomics (basal body proteome data) Nature genetics Medium 16415886
2009 Loss of mouse Mks1 in vivo leads to defective cilia formation in most tissues and altered Hedgehog (Hh) pathway signaling (both expansion and reduction of Shh signaling domains depending on tissue), demonstrating that Mks1 is required for ciliogenesis and Hh signal transduction in vivo. Mouse knockout, neural tube and limb patterning analysis, immunostaining for Hh pathway components Human molecular genetics High 19776033
2009 MKS1 and its related B9-domain proteins (MKSR-1, MKSR-2) localize to transition zones/basal bodies of sensory cilia in C. elegans in a co-dependent manner; disruption of human MKSR1 or MKSR2 causes ciliogenesis defects; genetic interactions among mks-1, mksr-1, mksr-2 double mutants manifest as increased lifespan through abnormal insulin-IGF-I signaling. GFP localization in C. elegans, RNAi/mutant analysis, ciliogenesis assays, genetic epistasis, lifespan assays Journal of cell science High 19208769
2009 Stable shRNA knockdown of Mks1 in IMCD3 cells induces multi-ciliated and multi-centrosomal phenotypes, demonstrating that MKS1 function is required for regulating appropriate cilia number and centrosome duplication. Stable shRNA knockdown, immunofluorescence for cilia and centrosomes Human molecular genetics Medium 19515853
2010 Mks1 localizes to the mother centriole in wild-type cells; a deletion mutation spanning the B9 domain (del64-323) abolishes mother centriole localization of Mks1, causing defective ciliogenesis of motile and non-motile cilia, disrupted planar cell polarity, and altered Shh signaling (impaired floor plate specification and expanded anterior Shh domain due to reduced Gli3R function). Mouse mutant analysis, immunofluorescence localization, node flow assay with fluorescent beads, neural tube and limb patterning analysis Disease models & mechanisms High 21045211
2011 High-confidence proteomics placed MKS1 within a distinct 'MKS module' of the NPHP/JBTS/MKS protein network linked to Hedgehog signaling, separate from the 'NPHP1-4-8' apical surface module and the 'NPHP5-6' centrosomal module; ciliary and Hh pathway defects downstream of MKS proteins contribute to retinal and neural deficits. Affinity purification/mass spectrometry proteomics, 3D renal culture ciliogenesis and morphogenesis assays, mouse knockout Cell High 21565611
2011 MKS1-related B9-domain protein B9d2 binds IFT particle components and contributes to ciliary localization of Inversin (Nephrocystin 2); this interaction network also supports transport of Opsin cargo but not Peripherin, and contributes to planar cell polarity in mechanosensory epithelia. Co-immunoprecipitation, morpholino knockdown in zebrafish, immunofluorescence The EMBO journal Medium 21602787
2015 MKS1 functions at the transition zone to regulate ciliary content of INPP5E through an ARL13B-dependent mechanism; patient fibroblasts with MKS1 mutations show decreased ciliary ARL13B and INPP5E, supporting a pathway where MKS1 → ARL13B → INPP5E controls ciliary phosphoinositide signaling. Immunofluorescence in patient fibroblasts, 3D spheroid rescue assay with mutant MKS1 alleles Journal of medical genetics Medium 26490104
2017 Genetic double-mutant analysis shows MKS1 cooperates with the BBSome (BBS4) for ciliary trafficking of ARL13B, a ciliary membrane protein; Mks1;Bbs4 double mutants exhibit exacerbated Hh patterning defects and ARL13B trafficking failure. MKS1 also genetically interacts with IFTB component Ift172 and the retrograde IFT motor Dync2h1, demonstrating that the MKS transition zone complex facilitates IFT to promote cilium assembly. Genetic epistasis (double mutant mouse embryos), immunofluorescence for ARL13B ciliary trafficking, Hh pathway analysis PloS one High 28291807
2020 MKS1 forms a complex with B9D2 and B9D1 in the order MKS1-B9D2-B9D1; their localization to the transition zone is interdependent; MKS1-KO and B9D2-KO cells show that this B9D protein complex is required to form a diffusion barrier for ciliary membrane proteins, maintaining distinct ciliary composition. Co-immunoprecipitation, knockout cell lines, rescue experiments, fluorescence recovery assays for diffusion barrier function Molecular biology of the cell High 32726168
2020 Genetic analysis in C. elegans shows mks-1 and mks-3 function in the same pathway, and combined disruption of the mks pathway with the nphp pathway (nphp-1/nphp-4) has synergistic effects on cilia positioning, orientation, and formation, demonstrating that MKS-1 acts in a pathway parallel to NPHP proteins. C. elegans genetic epistasis, cilia morphology and chemoreception assays Journal of the American Society of Nephrology Medium 20150540
2022 MKS1 interacts with UBE2E1 (an E2 ubiquitin-conjugating enzyme) and RNF34 (an E3 ligase); UBE2E1 and MKS1 co-localize at the ciliary base; UBE2E1 mediates both regulatory and degradative ubiquitination of MKS1; levels of UBE2E1 and MKS1 are co-dependent; UBE2E1 polyubiquitinates β-catenin, and processing of phosphorylated β-catenin occurs at the ciliary base through the functional MKS1-UBE2E1 interaction, regulating canonical Wnt signaling. Co-immunoprecipitation, co-localization, mouse Mks1 knockout model, ubiquitination assays, Wnt signaling readouts eLife High 35170427
2020 B9 domain of MKS1 is essential for the integrity of the B9 protein complex (with B9D2) and for localization of MKS1 to the ciliary transition zone; a frameshift mutation disrupting the B9 domain attenuates MKS1-B9D2 interaction and impairs TZ localization. Co-immunoprecipitation, immunofluorescence in patient-derived fibroblasts, mutant construct expression Frontiers in genetics Medium 33193692
2002 In yeast (Saccharomyces cerevisiae), Mks1p is a negative regulator of the RTG mitochondria-to-nucleus signaling pathway, acting between Rtg2p (a proximal sensor of mitochondrial dysfunction) and the bHLH transcription factors Rtg1p/Rtg3p; Mks1p is a phosphoprotein whose phosphorylation parallels Rtg3p, and Mks1p is in a complex with Rtg2p; in mks1Δ cells, RTG target gene expression is constitutive and resistant to glutamate repression. Genetic deletion analysis, co-immunoprecipitation (Mks1p-Rtg2p complex), phosphorylation analysis, gene expression assays Molecular biology of the cell Medium 11907262

Source papers

Stage 0 corpus · 41 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2011 Mapping the NPHP-JBTS-MKS protein network reveals ciliopathy disease genes and pathways. Cell 507 21565611
2005 The MAP kinase substrate MKS1 is a regulator of plant defense responses. The EMBO journal 371 15990873
2006 MAPKAP kinases - MKs - two's company, three's a crowd. Nature reviews. Molecular cell biology 324 16421520
2008 Arabidopsis mitogen-activated protein kinase kinases MKK1 and MKK2 have overlapping functions in defense signaling mediated by MEKK1, MPK4, and MKS1. Plant physiology 230 18599650
2006 The Meckel-Gruber Syndrome proteins MKS1 and meckelin interact and are required for primary cilium formation. Human molecular genetics 209 17185389
2006 MKS1, encoding a component of the flagellar apparatus basal body proteome, is mutated in Meckel syndrome. Nature genetics 184 16415886
2009 A mouse model for Meckel syndrome reveals Mks1 is required for ciliogenesis and Hedgehog signaling. Human molecular genetics 113 19776033
2009 Ciliary and centrosomal defects associated with mutation and depletion of the Meckel syndrome genes MKS1 and MKS3. Human molecular genetics 100 19515853
2002 RTG-dependent mitochondria-to-nucleus signaling is regulated by MKS1 and is linked to formation of yeast prion [URE3]. Molecular biology of the cell 86 11907262
2011 Nephrocystins and MKS proteins interact with IFT particle and facilitate transport of selected ciliary cargos. The EMBO journal 81 21602787
2010 Disruption of Mks1 localization to the mother centriole causes cilia defects and developmental malformations in Meckel-Gruber syndrome. Disease models & mechanisms 72 21045211
2007 Spectrum of MKS1 and MKS3 mutations in Meckel syndrome: a genotype-phenotype correlation. Mutation in brief #960. Online. Human mutation 72 17397051
2016 MAPK-Activated Protein Kinases (MKs): Novel Insights and Challenges. Frontiers in cell and developmental biology 71 26779481
2011 B9D1 is revealed as a novel Meckel syndrome (MKS) gene by targeted exon-enriched next-generation sequencing and deletion analysis. Human molecular genetics 67 21493627
2009 Functional interactions between the ciliopathy-associated Meckel syndrome 1 (MKS1) protein and two novel MKS1-related (MKSR) proteins. Journal of cell science 66 19208769
2010 Arabidopsis MKS1 is involved in basal immunity and requires an intact N-terminal domain for proper function. PloS one 59 21203436
2007 Molecular diagnostics of Meckel-Gruber syndrome highlights phenotypic differences between MKS1 and MKS3. Human genetics 58 17377820
2010 Normal ciliogenesis requires synergy between the cystic kidney disease genes MKS-3 and NPHP-4. Journal of the American Society of Nephrology : JASN 53 20150540
1993 Characterization of the MKS1 gene, a new negative regulator of the Ras-cyclic AMP pathway in Saccharomyces cerevisiae. Molecular & general genetics : MGG 43 8386801
2015 MKS1 regulates ciliary INPP5E levels in Joubert syndrome. Journal of medical genetics 42 26490104
2017 The Meckel syndrome- associated protein MKS1 functionally interacts with components of the BBSome and IFT complexes to mediate ciliary trafficking and hedgehog signaling. PloS one 38 28291807
2015 Identification of a novel MKS locus defined by TMEM107 mutation. Human molecular genetics 38 26123494
2000 A protein required for prion generation: [URE3] induction requires the Ras-regulated Mks1 protein. Proceedings of the National Academy of Sciences of the United States of America 38 10823922
2020 MKS-NPHP module proteins control ciliary shedding at the transition zone. PLoS biology 31 32163404
2020 Formation of the B9-domain protein complex MKS1-B9D2-B9D1 is essential as a diffusion barrier for ciliary membrane proteins. Molecular biology of the cell 26 32726168
2011 Constitutive expression of MKS1 confers susceptibility to Botrytis cinerea infection independent of PAD3 expression. Plant signaling & behavior 21 21900742
2007 Aberrant splicing is a common mutational mechanism in MKS1, a key player in Meckel-Gruber syndrome. Human mutation 21 17437276
2007 Phosphorylation sites of Arabidopsis MAP kinase substrate 1 (MKS1). Biochimica et biophysica acta 19 17702678
2007 A disease causing deletion of 29 base pairs in intron 15 in the MKS1 gene is highly associated with the campomelic variant of the Meckel-Gruber syndrome. Clinical genetics 17 17935508
2016 A Screen for Modifiers of Cilia Phenotypes Reveals Novel MKS Alleles and Uncovers a Specific Genetic Interaction between osm-3 and nphp-4. PLoS genetics 16 26863025
2016 MKS1 mutations cause Joubert syndrome with agenesis of the corpus callosum. European journal of medical genetics 14 27377014
2022 Regulation of canonical Wnt signalling by the ciliopathy protein MKS1 and the E2 ubiquitin-conjugating enzyme UBE2E1. eLife 12 35170427
1989 Analysis of a large-T-antigen variant expressed in simian virus 40-transformed mouse cell line mKS-A. Journal of virology 8 2542592
2016 Hypomorphic MKS1 mutation in a Pakistani family with mild Joubert syndrome and atypical features: Expanding the phenotypic spectrum of MKS1-related ciliopathies. American journal of medical genetics. Part A 7 27570071
1991 SDZ MKS 492. Agents and actions. Supplements 7 1793072
2021 Mild Clinical Presentation of Joubert Syndrome in a Male Adult Carrying Biallelic MKS1 Truncating Variants. Diagnostics (Basel, Switzerland) 6 34359301
2020 Novel Compound Heterozygous Variants in MKS1 Leading to Joubert Syndrome. Frontiers in genetics 6 33193692
2022 Case Report: Preimplantation Genetic Testing for Meckel Syndrome Induced by Novel Compound Heterozygous Mutations of MKS1. Frontiers in genetics 4 35360848
2025 Adiponectin Assists Thrombopoietic Agents in ITP Treatment by Enhancing Myosin-9/Rab6A-Mediated Trafficking of c-Mpl in MKs. Advanced science (Weinheim, Baden-Wurttemberg, Germany) 1 40558825
2021 Immunophenotyping and Cell Sorting of Human MKs from Human Primary Sources or Differentiated In Vitro from Hematopoietic Progenitors. Journal of visualized experiments : JoVE 1 34424238
2024 Deciphering Transcriptomic Variations in Hematopoietic Lineages: HSCs, EBs, and MKs. International journal of molecular sciences 0 39337559