Affinage

IFT43

Intraflagellar transport protein 43 homolog · UniProt Q96FT9

Length
208 aa
Mass
23.5 kDa
Annotated
2026-04-28
34 papers in source corpus 12 papers cited in narrative 12 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

IFT43 is a peripheral subunit of the intraflagellar transport complex A (IFT-A) that mediates retrograde ciliary transport, the movement of protein cargoes from the ciliary tip back to the cell body. Within IFT-A, IFT43 directly binds IFT121 and forms a peripheral subcomplex with IFT121 and IFT139 that is distinct from the IFT122/IFT140/IFT144 core; this peripheral subcomplex is essential for retrograde trafficking of IFT-B particles and G protein-coupled receptors including Smoothened, GPR161, and EP4, and for regulating Gli2/Gli3 processing that balances Hedgehog pathway activator and repressor output (PMID:22170070, PMID:27932497, PMID:41372612, PMID:41648367). Loss-of-function mutations in IFT43 cause IFT-B accumulation at ciliary tips, shortened cilia, and defective ciliogenesis, and are causative for Sensenbrenner syndrome (cranioectodermal dysplasia), short-rib polydactyly syndrome, and non-syndromic retinal degeneration (PMID:21378380, PMID:28400947, PMID:28973684). IFT43 moves bidirectionally within cilia and its cytoplasmic localization depends on the small GTPase Rsg1, linking planar cell polarity signaling to IFT-A positioning (PMID:25243405, PMID:24192041).

Mechanistic history

Synthesis pass · year-by-year structured walk · 7 steps
  1. 2011 High

    Establishing IFT43 as an IFT-A subunit required for retrograde ciliary transport resolved its molecular identity and linked it to a specific ciliary trafficking step: patient cells carrying a homozygous IFT43 initiation-codon mutation showed IFT-B accumulation at the ciliary tip with intact anterograde transport, defining IFT43 as a retrograde-specific factor and implicating it in Sensenbrenner syndrome.

    Evidence Western blot for truncated protein expression; immunofluorescence of IFT-B distribution in patient-derived Sensenbrenner syndrome fibroblasts

    PMID:21378380

    Open questions at the time
    • No direct rescue/complementation experiment to confirm causality of the IFT43 mutation alone
    • Molecular mechanism by which IFT43 contributes to retrograde motor engagement unknown
  2. 2011 High

    Determining that IFT43 directly binds IFT121 and exists as both a free cytoplasmic pool and a complex-associated pool defined IFT43's position as a peripheral/satellite component of IFT-A rather than part of the stable core.

    Evidence Yeast two-hybrid, recombinant co-expression in E. coli, sucrose gradient sedimentation, and analysis of Chlamydomonas ift121/ift122 mutants

    PMID:22170070

    Open questions at the time
    • Structural basis of IFT43–IFT121 interaction unresolved
    • Function of the free cytoplasmic IFT43 pool unknown
  3. 2013 Medium

    Showing that Rsg1 GTPase controls the cytoplasmic localization of IFT43 in multiciliated cells linked planar cell polarity effector pathways to retrograde IFT-A positioning, addressing how IFT43 reaches its site of action.

    Evidence Morpholino knockdown of Rsg1 in Xenopus multiciliated cells; immunofluorescence for IFT43 localization and live IFT imaging

    PMID:24192041

    Open questions at the time
    • Whether Rsg1 acts directly on IFT43 or indirectly through IFT121/IFT139 not distinguished
    • Not validated in mammalian systems
  4. 2014 Medium

    Live imaging of GFP-IFT43 revealed its bidirectional transport at ~0.45 µm/s in mammalian cilia and demonstrated that ICK kinase modulates IFT velocities, establishing that IFT43 undergoes regulated active transport rather than passive diffusion.

    Evidence Live imaging of GFP-IFT43 in IMCD-3 cells; ICK knockdown/overexpression and rapamycin treatment

    PMID:25243405

    Open questions at the time
    • Whether ICK acts directly on IFT43 or on the motor machinery not resolved
    • Single cell line used
  5. 2016 High

    Mapping the IFT-A peripheral subcomplex (IFT43/IFT121/IFT139) as functionally distinct from the core (IFT122/IFT140/IFT144) showed that the peripheral subcomplex is specifically required for retrograde trafficking of GPCRs (Smoothened, GPR161) and IFT particles, whereas the core mediates TULP3-dependent cargo import.

    Evidence VIP assay for subcomplex interactions; IFT139-KO and IFT144-KO cell immunofluorescence phenotype comparison

    PMID:27932497

    Open questions at the time
    • Direct contribution of IFT43 versus IFT139 versus IFT121 within the peripheral subcomplex not individually dissected
    • No structural resolution of the peripheral subcomplex
  6. 2017 Medium

    Demonstrating that IFT43 mutations cause SRPS with disrupted growth plate architecture and that IFT43 localizes to photoreceptors where its mutation causes retinal degeneration expanded the disease spectrum beyond Sensenbrenner syndrome and confirmed IFT43's essential role in ciliogenesis across tissue contexts.

    Evidence Patient mutation analysis, growth plate histology, and cilia length quantification in cells expressing mutant versus wild-type IFT43

    PMID:28400947 PMID:28973684

    Open questions at the time
    • Rescue experiments not performed for the retinal degeneration allele
    • Tissue-specific functions of IFT43 versus general ciliogenesis defect not distinguished
  7. 2025 Medium

    Identifying EP4 as a direct physical interactor of IFT43 through its IC3 loop and C-terminal region demonstrated that IFT43 functions not only as a general retrograde transport component but also as a cargo-specific adaptor for GPCR ciliary trafficking.

    Evidence Co-immunoprecipitation of EP4–IFT43 complex; high-content siRNA screen; CRISPR base editing of EP4 ciliary localization motif in zebrafish and mammalian cells

    PMID:41372612

    Open questions at the time
    • Whether IFT43 mediates EP4 import, export, or both not fully resolved
    • Reciprocal IP or in vitro reconstitution of direct binding not shown
    • Stoichiometry and competition with other GPCR cargoes unknown

Open questions

Synthesis pass · forward-looking unresolved questions
  • The mechanism by which IFT43 regulates Gli2/Gli3 processing and sets the activator/repressor balance downstream of Smoothened remains incompletely defined, as does the structural basis for IFT43's interactions within the peripheral subcomplex and with GPCR cargoes.
  • No high-resolution structure of IFT43 or the IFT43/IFT121 interface
  • Mechanism coupling IFT43 to Gli processing machinery unknown
  • Whether IFT43's free cytoplasmic pool has a cilium-independent function is untested

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060090 molecular adaptor activity 2
Localization
GO:0005929 cilium 5 GO:0005829 cytosol 2
Pathway
R-HSA-162582 Signal Transduction 3 R-HSA-1852241 Organelle biogenesis and maintenance 3 R-HSA-9609507 Protein localization 3
Partners
EP4IFT139RSG1WDR35
Complex memberships
IFT-A complexIFT-A peripheral subcomplex (IFT43/IFT121/IFT139)

Evidence

Reading pass · 12 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2011 IFT43 is a subunit of the IFT complex A (IFT-A) peripheral subcomplex involved in retrograde ciliary transport. A homozygous mutation in the IFT43 initiation codon (C14ORF179) disrupts translation, producing a shorter protein from a downstream ATG, and causes accumulation of IFT complex B proteins at the ciliary tip due to failed retrograde transport from the ciliary tip to its base, while anterograde transport remains functional. Western blot (mutation effect on translation), immunofluorescence of ciliated fibroblasts from Sensenbrenner syndrome patients showing IFT-B accumulation at ciliary tip Journal of medical genetics High 21378380
2011 IFT43 directly interacts with IFT121 within the IFT-A complex. IFT43 associates with the full 16S IFT-A complex in both cell bodies and flagella, but a significant fraction of cell body IFT43 exists as a smaller ~2S species not associated with the IFT-A complex. A core subcomplex of IFT144/IFT140/IFT122 (12S) exists independently, placing IFT43 and IFT121 as peripheral/satellite components. Sucrose density gradient centrifugation, antibody pulldowns, yeast two-hybrid, heterologous recombinant protein co-expression in E. coli, analysis of ift121 and ift122 mutants (Chlamydomonas reinhardtii ortholog) The Journal of biological chemistry High 22170070
2016 IFT43 is part of the peripheral IFT-A subcomplex (with IFT121/IFT139), distinct from the core subcomplex (IFT122/IFT140/IFT144) that associates with TULP3. The peripheral subcomplex, with IFT139 most distally located, is essential for retrograde trafficking of IFT-A, IFT-B, and G protein-coupled receptors (GPCRs) including Smoothened and GPR161 from the ciliary tip. Visible immunoprecipitation (VIP) assay to detect protein-protein interactions; IFT139-KO and IFT144-KO cell analysis by immunofluorescence showing distinct phenotypes in GPCR and IFT complex localization Molecular biology of the cell High 27932497
2014 IFT43 moves bidirectionally within cilia at ~0.45 µm/s in both anterograde and retrograde directions in mouse renal epithelial (IMCD-3) cells, consistent with being transported by the IFT machinery. Live imaging of GFP-tagged IFT43 demonstrated these dynamics, and knockdown of ICK kinase increased anterograde IFT velocities while overexpression reduced retrograde speed, suggesting ICK regulates IFT dynamics through the mTORC1 pathway. Live imaging of fluorescently tagged IFT43 (GFP-IFT43) in IMCD-3 cells; ICK/MOK knockdown and overexpression experiments; rapamycin treatment PloS one Medium 25243405
2017 IFT43 mutations cause short rib polydactyly syndrome (SRPS) by disrupting ciliogenesis and cartilage growth plate architecture, leading to altered endochondral ossification. IFT43 is essential for ciliogenesis, and its loss disrupts the orderly proliferation and differentiation of growth plate chondrocytes. The phenotypic similarity with IFT121 (WDR35) mutations confirms that IFT43 and its direct interactor IFT121 operate in the same pathway. Patient mutation analysis, histological analysis of growth plate architecture, ciliary immunofluorescence in patient-derived cells, genetic epistasis with IFT121 mutations Cilia Medium 28400947
2017 A homozygous missense mutation in IFT43 (c.100 G>A) causes non-syndromic recessive retinal degeneration. IFT43 localizes to the photoreceptors and to the tip of cilia in transfected mIMCD3 and MDCK cells. Expression of mutant IFT43 results in significantly shorter cilia compared to wild-type IFT43, demonstrating a role for IFT43 in maintaining normal cilia length. RT-PCR, western blot, immunohistochemistry in retina and transfected cell lines (mIMCD3, MDCK); cilia length measurement comparing wild-type vs mutant IFT43 expressing cells Human molecular genetics Medium 28973684
2013 The small GTPase Rsg1 (a binding partner of the planar cell polarity effector Fuz) is required for appropriate cytoplasmic localization of the retrograde IFT-A protein IFT43 in Xenopus multiciliated cells. Loss of Rsg1 impairs axonemal IFT dynamics and disrupts apical trafficking of basal bodies. Loss-of-function (morpholino knockdown) in Xenopus multiciliated cells; live imaging of IFT dynamics; immunofluorescence for IFT43 cytoplasmic localization Cilia Medium 24192041
2017 In Chlamydomonas, loss of IFT54 (IFT-B component) causes accumulation of IFT-A component IFT43 (along with IFT-B component IFT46) at the flagellar tip in cells expressing only the CC domain of IFT54, indicating that IFT54 functions in IFT turnaround at the flagellar tip and that IFT43 accumulation is a readout of failed retrograde transport initiation. Chlamydomonas ift54 mutant rescue experiments with domain-deletion constructs; immunofluorescence showing IFT43 accumulation at flagellar tip Cellular and molecular life sciences : CMLS Medium 28417161
2025 IFT43 physically interacts with the GPCR prostaglandin E receptor 4 (EP4) through EP4's third intracellular (IC3) loop and C-terminal (CT) region. IFT43 functions as a crucial regulator of EP4 ciliary trafficking in zebrafish and mammalian cells. High-content siRNA screening identified IFT43 alongside Rab23 GTPase as regulators of EP4 entry into primary cilia. High-content siRNA screen; co-immunoprecipitation (physical interaction between EP4 and IFT43); CRISPR C-to-G base editing (CGBE1) of EP4 LPG ciliary localization motif; immunofluorescence in zebrafish embryos, mouse tissues, and human cells Communications biology Medium 41372612
2016 Haploinsufficiency of IFT43 (via a de novo 14q24.2q24.3 microdeletion) leads to increased accumulation of IFT-B proteins at the ciliary tip in patient-derived fibroblasts compared to controls, demonstrating defective retrograde ciliary transport even with loss of one allele. Immunocytochemistry in patient-derived fibroblasts showing IFT-B protein distribution; array CGH for deletion mapping; Sanger and exome sequencing of second allele American journal of medical genetics. Part A Low 26892345
2020 Under simulated microgravity (SMG), the ratio of anterograde (IFT88) to retrograde (IFT43) IFT particle numbers and protein expression increases in osteocytes, and anterograde IFT particle size decreases, indicating that SMG disrupts the balanced operating state of IFT and shifts the anterograde/retrograde balance, correlating with cilia shortening. Live imaging with GFP::IFT88 (anterograde) and OFP::IFT43 (retrograde) tagged proteins in osteocytes under simulated microgravity; particle counting and size measurement; western blot for protein expression Biochemical and biophysical research communications Low 32828281
2026 Loss of Ift43 in mice causes mid-gestation lethality with severe craniofacial, neural tube, abdominal wall, and limb patterning defects. At the cellular level, Ift43 deficiency reduces cilia number and length, blocks Gli1 induction by Hedgehog pathway activation, causes abnormal accumulation of Gli2 and Gli3 at ciliary tips before stimulation, and fails to suppress Gli repressor forms after activation. Conversely, Ift43 overexpression increases basal Gli2 cleavage, revealing a role for Ift43 in regulating Gli processing and setting the balance between Gli activator and repressor forms downstream of Smoothened (which still relocalizes to cilia normally). Mouse Ift43 knockout (loss-of-function), immunofluorescence for Gli2/Gli3/Smoothened ciliary localization, Gli1 reporter induction by SAG agonist, Ift43 overexpression Gli2 cleavage assay bioRxivpreprint Medium 41648367

Source papers

Stage 0 corpus · 34 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2012 Ciliary disorder of the skeleton. American journal of medical genetics. Part C, Seminars in medical genetics 193 22791528
2011 C14ORF179 encoding IFT43 is mutated in Sensenbrenner syndrome. Journal of medical genetics 122 21378380
2016 Intraflagellar transport-A complex mediates ciliary entry and retrograde trafficking of ciliary G protein-coupled receptors. Molecular biology of the cell 118 27932497
2011 Subunit interactions and organization of the Chlamydomonas reinhardtii intraflagellar transport complex A proteins. The Journal of biological chemistry 91 22170070
2014 Regulation of cilium length and intraflagellar transport by the RCK-kinases ICK and MOK in renal epithelial cells. PloS one 81 25243405
2018 Ciliopathy-associated mutations of IFT122 impair ciliary protein trafficking but not ciliogenesis. Human molecular genetics 53 29220510
2017 IFT54 regulates IFT20 stability but is not essential for tubulin transport during ciliogenesis. Cellular and molecular life sciences : CMLS 35 28417161
2017 Mutations in IFT-A satellite core component genes IFT43 and IFT121 produce short rib polydactyly syndrome with distinctive campomelia. Cilia 28 28400947
2021 Molecular basis of ciliary defects caused by compound heterozygous IFT144/WDR19 mutations found in cranioectodermal dysplasia. Human molecular genetics 24 33517396
2013 The Small GTPase Rsg1 is important for the cytoplasmic localization and axonemal dynamics of intraflagellar transport proteins. Cilia 19 24192041
2020 Epigenome-wide association study identifies DNA methylation sites associated with target organ damage in older African Americans. Epigenetics 18 33100131
2016 Novel IFT122 mutations in three Argentinian patients with cranioectodermal dysplasia: Expanding the mutational spectrum. American journal of medical genetics. Part A 18 26792575
2020 Compound heterozygous IFT140 variants in two Polish families with Sensenbrenner syndrome and early onset end-stage renal disease. Orphanet journal of rare diseases 16 32007091
2017 A mutation in IFT43 causes non-syndromic recessive retinal degeneration. Human molecular genetics 16 28973684
2019 Ttc39c is upregulated during skeletal muscle atrophy and modulates ERK1/2 MAP kinase and hedgehog signaling. Journal of cellular physiology 14 31188487
2014 Control elements targeting Tgfb3 expression to the palatal epithelium are located intergenically and in introns of the upstream Ift43 gene. Frontiers in physiology 11 25071603
2023 A whole exome sequencing study to identify rare variants in multiplex families with alcohol use disorder. Frontiers in psychiatry 9 37915799
2020 Prenatal genetic diagnosis of cranioectodermal dysplasia in a Polish family with compound heterozygous variants in WDR35. American journal of medical genetics. Part A 9 32804427
2020 The microgravity induces the ciliary shortening and an increased ratio of anterograde/retrograde intraflagellar transport of osteocytes. Biochemical and biophysical research communications 8 32828281
2019 A new case of KIAA0753-related variant of Jeune asphyxiating thoracic dystrophy. European journal of medical genetics 7 31816441
2017 Clinical and molecular genetic characterization of a male patient with Sensenbrenner syndrome (cranioectodermal dysplasia) and biallelic WDR35 mutations. Birth defects research 7 29134781
2020 Primary ciliary dyskinesia relative protein ZMYND10 is involved in regulating ciliary function and intraflagellar transport in Paramecium tetraurelia. European journal of protistology 6 33279757
2024 Genetic profiling of azoospermic men to identify the etiology and predict reproductive potential. Journal of assisted reproduction and genetics 3 38403804
2024 Identification of the principal neuropeptide MIP and its action pathway in larval settlement of the echiuran worm Urechis unicinctus. BMC genomics 3 38641568
2016 De novo 14q24.2q24.3 microdeletion including IFT43 is associated with intellectual disability, skeletal anomalies, cardiac anomalies, and myopia. American journal of medical genetics. Part A 3 26892345
2024 Genome-wide association study and meta-analysis of phytosterols identifies a novel locus for serum levels of campesterol. Human genomics 2 39090729
2023 Ciliary phenotyping in renal epithelial cells in a cranioectodermal dysplasia patient with WDR35 variants. Frontiers in molecular biosciences 1 38161384
2023 Reanalysis of Whole-Exome Sequencing Data of an Infant with Suspected Diagnosis of Jeune Syndrome Revealed a Likely Pathogenic Variant in GRK2: A Newly Associated Gene for Jeune Syndrome Phenotype. Molecular syndromology 1 38585547
2018 [Clinical features and mutational analysis of a case with Sensenbrenner syndrome]. Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics 1 29896747
2026 Ift43 Controls the Ciliary Levels of Gli2 and Gli3. bioRxiv : the preprint server for biology 0 41648367
2025 Maternal and Parent-of-Origin Gene-Environment Effects on the Etiology of Orofacial Clefting. Genes 0 40004524
2025 [Two cases of skeletal ciliopathies in one family]. Zeitschrift fur Geburtshilfe und Neonatologie 0 40749718
2025 Rab23 GTPase and IFT43 regulate the trafficking of prostaglandin E receptor 4 to primary cilia. Communications biology 0 41372612
2023 Canonical Wnt signaling is not required for Tgfb3 expression in the basal medial edge epithelium during palatogenesis. Frontiers in physiology 0 37250135