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this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.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.
Human DYNLT2B, also known as TCTEX1D2, encodes a 142-amino-acid, non-catalytic Tctex-family dynein light chain. Its best-supported primary function is as a structural and interaction subunit of cytoplasmic dynein-2, the minus-end-directed motor that powers retrograde intraflagellar transport (IFT) from the ciliary tip toward the cell body. DYNLT2B forms an asymmetric 1:1 heterodimer with DYNLT1 in the light-chain region of the dynein-2 tail and associates mainly with the WDR60 intermediate-chain arm. It therefore has no enzymatic reaction, small-molecule substrate, or transporter pore; its “substrates” in a broad functional sense are protein complexes and IFT cargo assemblies whose movement is powered by DYNC2H1 ATPase activity rather than by DYNLT2B itself. (vuolo2020cytoplasmicdynein2at pages 3-4, mukhopadhyay2024structureandtethering pages 3-4, asante2014subunitcompositionof pages 1-4)
The strongest cellular evidence places DYNLT2B at centrosomes, microtubule-organizing centers and the base of primary cilia, where it contributes to cilium formation and homeostasis. A role in retrograde IFT is strongly supported by its dynein-2 membership and ciliary phenotypes, but no unique DYNLT2B-bound cargo has been demonstrated. Human disease evidence is substantially thinner than the biochemical evidence and should not be conflated with the well-established ciliopathy genes WDR34, WDR60, DYNC2H1, or DYNC2LI1. (gholkar2015tctex1d2associateswith pages 7-9, gholkar2015tctex1d2associateswith pages 5-6, asante2014subunitcompositionof pages 4-5)
The target specified by the user is internally consistent:
Recent structural work explicitly uses the combined designation DYNLT2B/TCTEX1D2, confirming that the current gene symbol and older literature name refer to the same human dynein-2 light chain. (mukhopadhyay2024structureandtethering pages 3-4)
Important exclusions are DYNLT1/TCTEX1, which is a different light chain that partners with DYNLT2B, and the Chlamydomonas protein TCTEX2B, which is not the human target. Literature about these similarly named proteins was not treated as direct evidence for human DYNLT2B.
Affinity proteomics and immunoprecipitation identified TCTEX1D2 in human dynein-2 assemblies containing WDR34 and WDR60. It was absent from the corresponding dynein-1 pull-downs in the foundational composition study, supporting its designation as the unique dynein-2-specific Tctex light chain. Other light-chain families, including LC8, Roadblock, DYNLT1 and DYNLT3, can be shared with dynein-1. (asante2014subunitcompositionof pages 1-4, asante2014subunitcompositionof pages 4-5)
Some earlier co-immunoprecipitations recovered DYNLT2B together with components annotated to both dynein-1 and dynein-2. Thus, “dynein-2-specific” is best understood as its established stable motor-complex assignment, not proof that it can never contact a dynein-1-associated protein. (gholkar2015tctex1d2associateswith pages 2-4, gholkar2015tctex1d2associateswith pages 4-5)
The clearest 2024 advance was biochemical and structural characterization of the isolated human DYNLT1–DYNLT2B heterodimer. Size-exclusion chromatography with multi-angle light scattering measured a 28.1-kDa species, consistent with a 1:1 heterodimer rather than a dimer of dimers, and its crystal structure was determined at 2 Å resolution. In the intact dynein-2 cryo-EM reconstruction, density at the base of the light-chain tower was consistent with this pair but was too weak for atomic model building. Therefore, heterodimer formation is directly demonstrated, while its exact contacts in the complete motor remain partly model-based. (mukhopadhyay2024structureandtethering pages 3-4)
Biochemical studies place the heterodimer principally on the WDR60 intermediate-chain arm. Full-length DYNLT2B and its C-terminal Tctex1-domain fragment bound WDR60 and WDR34, whereas the N-terminal fragment displayed little or minimal binding. One affinity purification recovered 561 WDR60 peptides, illustrating the strength of this association. Predicted interfaces involving WDR60 residues D469–P512 and WDR34 residues P37–50 remain computational assignments rather than fully resolved atomic contacts. (gholkar2015tctex1d2associateswith pages 4-5, mukhopadhyay2024structureandtethering pages 3-4)
Accordingly, the most defensible molecular annotation is:
A non-catalytic dynein-2 tail subunit that forms a DYNLT1–DYNLT2B heterodimer, stabilizes or organizes intermediate/light-chain interactions, and helps support assembly, ciliary targeting, or operation of the retrograde IFT motor.
Whether DYNLT2B is also a classical cargo adaptor is unresolved. The variable N-termini of Tctex-family proteins are often discussed as cargo-binding regions, but no specific DYNLT2B-dependent cargo has been established. Proposed candidates such as MKS3, BBS7 or centrosomal proteins remain interaction candidates rather than validated transported substrates. (gholkar2015tctex1d2associateswith pages 2-4, gholkar2015tctex1d2associateswith pages 7-9)
Endogenous human TCTEX1D2 was detected around centrioles and at the ciliary base/basal body in ciliated hTERT-RPE cells. In cycling cells it also localized to microtubule-organizing centers, mitotic spindle poles, centrosomal regions and cytokinetic-bridge microtubules. Localization to the MTOC or ciliary base was disrupted by microtubule depolymerization and depended on WDR60, whereas WDR60 remained at the ciliary base following TCTEX1D2 depletion. This indicates that WDR60 is upstream of, or required for, DYNLT2B recruitment. (gholkar2015tctex1d2associateswith pages 7-9, gholkar2015tctex1d2associateswith pages 5-6, gholkar2015tctex1d2associateswith pages 6-7, gholkar2015tctex1d2associateswith pages 4-5)
Tagged, overexpressed TCTEX1D2 was additionally seen along the ciliary axoneme, but endogenous axonemal signal was not robustly detected. The strongest localization assignment is therefore the ciliary base/centrosome, with intraxonemal localization plausible but less secure. (gholkar2015tctex1d2associateswith pages 7-9, gholkar2015tctex1d2associateswith pages 5-6)
Dynein-2 is carried anterogradely to the ciliary tip on IFT trains and then powers retrograde movement toward the basal body. This trafficking recycles IFT components and removes material from the tip, thereby sustaining ciliary assembly, signaling and length control. DYNLT2B participates as a non-motor tail subunit; force and ATP hydrolysis are supplied by the DYNC2H1 heavy chains. (vuolo2020cytoplasmicdynein2at pages 3-4, asante2014subunitcompositionof pages 1-4)
The connection to retrograde IFT is strongest at the motor-complex level. Protein-specific support includes dynein-2 association, ciliary-base localization, altered ciliogenesis after depletion and tip-associated abnormalities in deficient fibroblasts. Nevertheless, no study in the retrieved evidence measured a unique cargo’s movement as specifically dependent on DYNLT2B, so its precise mechanochemical contribution remains unresolved. (gholkar2015tctex1d2associateswith pages 7-9, vuolo2020cytoplasmicdynein2at pages 3-4, roberts2018emergingmechanismsof pages 13-14)
Human-cell depletion results differ somewhat with cell system and assay:
These apparently divergent findings likely reflect differences in knockdown efficiency, cell background, serum-starvation protocol and measured endpoint. Collectively, they support a role in ciliary assembly and length/homeostatic control, but not an invariant requirement for the earliest step of axoneme initiation.
Primary cilia organize developmental signaling pathways, particularly Hedgehog signaling. Dynein-2 defects can disrupt the ciliary distributions of receptors, IFT particles and signaling proteins. For DYNLT2B specifically, however, the retrieved experiments primarily establish motor-complex membership and ciliary defects; they do not define a direct biochemical action on a Hedgehog component. Hedgehog dysregulation should therefore be considered a plausible downstream consequence of impaired retrograde IFT rather than a DYNLT2B-specific signaling reaction. Recent CEP170 work showed that destabilizing dynein-2 assembly perturbs IFT and Hedgehog signaling, but TCTEX1D2 was only listed as a complex subunit rather than tested individually. (weijman2024rolesforcep170 pages 1-3)
Secondary literature links biallelic TCTEX1D2 defects with Jeune asphyxiating thoracic dystrophy/short-rib thoracic dysplasia, a skeletal ciliopathy, and reports impaired IFT-associated phenotypes in patient fibroblasts. One review noted abnormal tip-associated material in approximately 35% of cilia in TCTEX1D2-deficient fibroblasts versus less than 10% of controls. (roberts2018emergingmechanismsof pages 13-14)
However, the accessible evidence did not provide a complete primary patient series, reliable allele list, cohort size, penetrance estimate or population frequency. Consequently:
There are no validated therapeutic agents, clinical trials or routine protein-targeted treatments for DYNLT2B deficiency in the retrieved literature. Present real-world use is primarily diagnostic interpretation in ciliopathy sequencing, supported by patient-cell ciliation/IFT assays when variants of uncertain significance are encountered.
The recent literature refines mechanism more than it expands human clinical genetics:
The 2023–2024 literature therefore strengthens a structural model in which DYNLT2B is an asymmetric light-chain partner embedded in the WDR60 side of dynein-2. It does not yet identify a unique cargo, regulatory ligand, or tractable drug-binding function.
The following table separates direct human findings from inference and preliminary non-human observations.
| Annotation claim | Evidence/model | Key quantitative result | Confidence/limitation |
|---|---|---|---|
| Human DYNLT2B is also called TCTEX1D2 and is a small Tctex1-domain light chain. | Human mapping and truncation studies used full-length TCTEX1D2 and localized WDR34/WDR60 binding predominantly to its conserved C-terminal Tctex1 domain. (gholkar2015tctex1d2associateswith pages 2-4, gholkar2015tctex1d2associateswith pages 4-5) | 142 aa; fragments tested: residues 1–40 and 41–142. | High for size and domain architecture. The proposed cargo-binding role of the variable N-terminus is family-based inference. |
| TCTEX1D2 is a dynein-2-specific, non-catalytic light-chain component. | Human WDR34 interactome and immunoprecipitation detected TCTEX1D2 in dynein-2 but not dynein-1 pull-downs; later syntheses classify it as the unique dynein-2-specific Tctex light chain. (asante2014subunitcompositionof pages 1-4, asante2014subunitcompositionof pages 4-5, vuolo2020cytoplasmicdynein2at pages 3-4) | No catalytic reaction or substrate is known. | High for stable dynein-2 assignment. Earlier recovery with components of both dyneins means specificity should not be interpreted as absence of every dynein-1 association. (gholkar2015tctex1d2associateswith pages 2-4, gholkar2015tctex1d2associateswith pages 4-5) |
| DYNLT2B forms an asymmetric light-chain pair with DYNLT1 in the dynein-2 tail. | Recombinant human DYNLT1–DYNLT2B was analyzed by SEC-MALS and X-ray crystallography, supporting a 1:1 heterodimer. (mukhopadhyay2024structureandtethering pages 3-4) | 28.1-kDa SEC-MALS species; 2 Å crystal structure. | High for the isolated heterodimer. Its density in intact dynein-2 was too weak for atomic model building. |
| TCTEX1D2 associates principally with the WDR60 arm of dynein-2. | Affinity purification, reciprocal co-immunoprecipitation, and truncation assays showed association with WDR60 and WDR34; the C-terminal Tctex1 domain mediated most binding. (gholkar2015tctex1d2associateswith pages 2-4, gholkar2015tctex1d2associateswith pages 4-5, mukhopadhyay2024structureandtethering pages 3-4) | One purification recovered 561 WDR60 peptides. | Moderate–high for biochemical association. Predicted contacts involving WDR60 residues D469–P512 and WDR34 residues P37–50 were not resolved atomically. |
| The protein localizes to centrosomal and ciliary microtubule-organizing regions. | Immunofluorescence detected endogenous TCTEX1D2 around centrioles and at the ciliary base; cycling cells also showed MTOC, spindle-pole, centrosomal, and cytokinetic-bridge localization. Localization was microtubule- and WDR60-dependent. (gholkar2015tctex1d2associateswith pages 7-9, gholkar2015tctex1d2associateswith pages 5-6, gholkar2015tctex1d2associateswith pages 6-7, gholkar2015tctex1d2associateswith pages 4-5) | No robust localization percentage was reported. | High for ciliary-base/MTOC localization. Axonemal localization was clearer for overexpressed tagged protein than for endogenous protein. |
| TCTEX1D2 contributes to ciliogenesis and ciliary homeostasis. | siRNA depletion in human hTERT-RPE cells reduced the ciliated-cell fraction; another study reported longer cilia without an obvious block in ciliogenesis. (gholkar2015tctex1d2associateswith pages 5-6, asante2014subunitcompositionof pages 5-6) | 27.3 ± 8.5% ciliated after depletion versus 64 ± 5.0% in controls. | Moderate–high for a role in cilia formation or function. The exact affected step and phenotype severity vary among assays. |
| TCTEX1D2 probably supports dynein-2-mediated retrograde intraflagellar transport but is not itself an ATPase or transporter pore. | Its dynein-2-tail placement, ciliary-base localization, and depletion phenotype support a structural/adaptor role in motor assembly or trafficking; specific cargoes were not demonstrated. (gholkar2015tctex1d2associateswith pages 7-9, vuolo2020cytoplasmicdynein2at pages 3-4, asante2014subunitcompositionof pages 1-4) | A review reported tip-associated abnormalities in about 35% of cilia in deficient patient fibroblasts versus less than 10% of controls. (roberts2018emergingmechanismsof pages 13-14) | Moderate because retrograde-IFT involvement is strong at the complex level, but no unique TCTEX1D2-dependent cargo or biochemical step is defined. |
| Human ciliopathy association is plausible, but gene-specific clinical evidence is limited. | Secondary literature links biallelic TCTEX1D2 mutations to Jeune/asphyxiating thoracic dystrophy and impaired IFT; foundational work initially described it as a candidate ciliopathy gene. (roberts2018emergingmechanismsof pages 13-14, asante2014subunitcompositionof pages 1-4) | No reliable patient count, allele frequency, or complete variant series was available in the extracted evidence. | Limited–moderate for gene–disease causality in this evidence set. Disease evidence for WDR34, WDR60, DYNC2H1, or DYNC2LI1 must not be attributed to DYNLT2B. |
| Tctex1d2 may have an additional role in mammalian sperm-flagellum assembly. | A June 2024 mouse-knockout preprint reported interactions with dynein-2 and inner-dynein-arm proteins; knockout males were infertile with sperm flagellar dysplasia, whereas other motile cilia appeared normal. (harima2024tctex1d2hastwo pages 1-3) | Infertility was reported in Tctex1d2-null male mice; no fertility rate was provided in the extracted passage. | Preliminary and non-human: this bioRxiv result should not yet be used to assign human infertility or a human axonemal-dynein function to DYNLT2B. |
Table: Evidence matrix separating direct human DYNLT2B/TCTEX1D2 findings from complex-level inference, limited clinical evidence, and preliminary non-human observations.
DYNLT2B/TCTEX1D2 is a human Tctex-family, non-enzymatic light chain of cytoplasmic dynein-2. It forms a 1:1 heterodimer with DYNLT1, associates predominantly with the WDR60 intermediate-chain arm, and functions at the centrosome/ciliary base and within the dynein-2 transport machinery to support ciliogenesis, ciliary homeostasis and retrograde IFT. Its exact cargo-binding or motor-regulatory step remains unknown. Human skeletal-ciliopathy association is plausible and reported, but the gene-specific clinical evidence is limited relative to the strong biochemical and cell-biological annotation.
References
(vuolo2020cytoplasmicdynein2at pages 3-4): Laura Vuolo, Nicola L. Stevenson, Aakash G. Mukhopadhyay, Anthony J. Roberts, and David J. Stephens. Cytoplasmic dynein-2 at a glance. Journal of Cell Science, Mar 2020. URL: https://doi.org/10.1242/jcs.240614, doi:10.1242/jcs.240614. This article has 42 citations and is from a domain leading peer-reviewed journal.
(mukhopadhyay2024structureandtethering pages 3-4): Aakash G Mukhopadhyay, Katerina Toropova, Lydia Daly, Jennifer N Wells, Laura Vuolo, Miroslav Mladenov, Marian Seda, Dagan Jenkins, David J Stephens, and Anthony J Roberts. Structure and tethering mechanism of dynein-2 intermediate chains in intraflagellar transport. The EMBO Journal, 43:1257-1272, Mar 2024. URL: https://doi.org/10.1038/s44318-024-00060-1, doi:10.1038/s44318-024-00060-1. This article has 16 citations.
(asante2014subunitcompositionof pages 1-4): David Asante, Nicola L. Stevenson, and David J. Stephens. Subunit composition of the human cytoplasmic dynein-2 complex. Journal of Cell Science, 127:4774-4787, Nov 2014. URL: https://doi.org/10.1242/jcs.159038, doi:10.1242/jcs.159038. This article has 127 citations and is from a domain leading peer-reviewed journal.
(gholkar2015tctex1d2associateswith pages 7-9): Ankur A. Gholkar, Silvia Senese, Yu-Chen Lo, Joseph Capri, William J Deardorff, Harish Dharmarajan, Ely Contreras, Emmanuelle Hodara, Julian P Whitelegge, Peter K Jackson, and Jorge Z Torres. Tctex1d2 associates with short-rib polydactyly syndrome proteins and is required for ciliogenesis. Cell Cycle, 14:1116-1125, Apr 2015. URL: https://doi.org/10.4161/15384101.2014.985066, doi:10.4161/15384101.2014.985066. This article has 34 citations and is from a peer-reviewed journal.
(gholkar2015tctex1d2associateswith pages 5-6): Ankur A. Gholkar, Silvia Senese, Yu-Chen Lo, Joseph Capri, William J Deardorff, Harish Dharmarajan, Ely Contreras, Emmanuelle Hodara, Julian P Whitelegge, Peter K Jackson, and Jorge Z Torres. Tctex1d2 associates with short-rib polydactyly syndrome proteins and is required for ciliogenesis. Cell Cycle, 14:1116-1125, Apr 2015. URL: https://doi.org/10.4161/15384101.2014.985066, doi:10.4161/15384101.2014.985066. This article has 34 citations and is from a peer-reviewed journal.
(asante2014subunitcompositionof pages 4-5): David Asante, Nicola L. Stevenson, and David J. Stephens. Subunit composition of the human cytoplasmic dynein-2 complex. Journal of Cell Science, 127:4774-4787, Nov 2014. URL: https://doi.org/10.1242/jcs.159038, doi:10.1242/jcs.159038. This article has 127 citations and is from a domain leading peer-reviewed journal.
(gholkar2015tctex1d2associateswith pages 2-4): Ankur A. Gholkar, Silvia Senese, Yu-Chen Lo, Joseph Capri, William J Deardorff, Harish Dharmarajan, Ely Contreras, Emmanuelle Hodara, Julian P Whitelegge, Peter K Jackson, and Jorge Z Torres. Tctex1d2 associates with short-rib polydactyly syndrome proteins and is required for ciliogenesis. Cell Cycle, 14:1116-1125, Apr 2015. URL: https://doi.org/10.4161/15384101.2014.985066, doi:10.4161/15384101.2014.985066. This article has 34 citations and is from a peer-reviewed journal.
(gholkar2015tctex1d2associateswith pages 4-5): Ankur A. Gholkar, Silvia Senese, Yu-Chen Lo, Joseph Capri, William J Deardorff, Harish Dharmarajan, Ely Contreras, Emmanuelle Hodara, Julian P Whitelegge, Peter K Jackson, and Jorge Z Torres. Tctex1d2 associates with short-rib polydactyly syndrome proteins and is required for ciliogenesis. Cell Cycle, 14:1116-1125, Apr 2015. URL: https://doi.org/10.4161/15384101.2014.985066, doi:10.4161/15384101.2014.985066. This article has 34 citations and is from a peer-reviewed journal.
(gholkar2015tctex1d2associateswith pages 6-7): Ankur A. Gholkar, Silvia Senese, Yu-Chen Lo, Joseph Capri, William J Deardorff, Harish Dharmarajan, Ely Contreras, Emmanuelle Hodara, Julian P Whitelegge, Peter K Jackson, and Jorge Z Torres. Tctex1d2 associates with short-rib polydactyly syndrome proteins and is required for ciliogenesis. Cell Cycle, 14:1116-1125, Apr 2015. URL: https://doi.org/10.4161/15384101.2014.985066, doi:10.4161/15384101.2014.985066. This article has 34 citations and is from a peer-reviewed journal.
(roberts2018emergingmechanismsof pages 13-14): Anthony J. Roberts. Emerging mechanisms of dynein transport in the cytoplasm versus the cilium. Biochemical Society Transactions, 46:967-982, Jul 2018. URL: https://doi.org/10.1042/bst20170568, doi:10.1042/bst20170568. This article has 77 citations and is from a peer-reviewed journal.
(gholkar2015tctex1d2associateswith pages 9-10): Ankur A. Gholkar, Silvia Senese, Yu-Chen Lo, Joseph Capri, William J Deardorff, Harish Dharmarajan, Ely Contreras, Emmanuelle Hodara, Julian P Whitelegge, Peter K Jackson, and Jorge Z Torres. Tctex1d2 associates with short-rib polydactyly syndrome proteins and is required for ciliogenesis. Cell Cycle, 14:1116-1125, Apr 2015. URL: https://doi.org/10.4161/15384101.2014.985066, doi:10.4161/15384101.2014.985066. This article has 34 citations and is from a peer-reviewed journal.
(asante2014subunitcompositionof pages 5-6): David Asante, Nicola L. Stevenson, and David J. Stephens. Subunit composition of the human cytoplasmic dynein-2 complex. Journal of Cell Science, 127:4774-4787, Nov 2014. URL: https://doi.org/10.1242/jcs.159038, doi:10.1242/jcs.159038. This article has 127 citations and is from a domain leading peer-reviewed journal.
(weijman2024rolesforcep170 pages 1-3): Johannes F Weijman, Laura Vuolo, Caroline Shak, Anna Pugnetti, Aakash G Mukhopadhyay, Lorna R Hodgson, Kate J Heesom, Anthony J Roberts, and David J Stephens. Roles for cep170 in cilia function and dynein-2 assembly. Journal of Cell Science, Nov 2024. URL: https://doi.org/10.1101/2023.11.20.567836, doi:10.1101/2023.11.20.567836. This article has 18 citations and is from a domain leading peer-reviewed journal.
(harima2024tctex1d2hastwo pages 1-3): Ryua Harima, Kenshiro Hara, and Kentaro Tanemura. Tctex1d2 has two distinct functions in sperm flagellum formation in mice; cytoplasmic dynein 2 and inner dynein arm. bioRxiv, Jun 2024. URL: https://doi.org/10.1101/2024.06.27.600786, doi:10.1101/2024.06.27.600786. This article has 0 citations.