YIF1B

YIF1B is an intracellular membrane scaffold of the ER-to-Golgi intermediate compartment that organizes anterograde vesicular trafficking and supports Golgi architectural integrity (PMID:26077767). Its best-defined role is as the direct receptor for the somatodendritic targeting of the 5-HT1A serotonin receptor: it binds a tribasic motif in the receptor's C-terminal tail with high affinity (KD ≈ 37 nM) and nucleates a vesicular complex containing Yip1A, Rab6, and Kif5B that co-traffics the receptor out of the soma into the dendritic tree, with knockdown of YIF1B or any complex partner abolishing distal dendritic targeting (PMID:18685031, PMID:23055492). YIF1B localizes to the intermediate compartment rather than as a Golgi resident and acts selectively in anterograde (ER-to-Golgi) transport while leaving retrograde traffic unaffected; its long-term loss disorganizes Golgi architecture as a mechanistically distinct consequence (PMID:26077767). The same anterograde trafficking activity handles additional cargo: YIF1B engages the transmembrane domain of the lysosomal ABC transporter TAPL/ABCB9 at its ER-to-Golgi step (PMID:30877195) and translocates SARS-CoV-2 ORF8 into vesicles for unconventional secretion via its α4 helix (PMID:39811650). In vivo, YIF1B loss reduces forebrain serotonergic projection density and 5-HT1A autoreceptor function with behavioral serotonergic deficits (PMID:32459080), and biallelic loss-of-function mutations cause a human neurodevelopmental syndrome featuring ER/Golgi alterations and primary cilia abnormalities, linking a Golgipathy to ciliopathy (PMID:33103737).

1. 2008 High

   Established that YIF1B is a dedicated trafficking partner of the 5-HT1A serotonin receptor, answering how this receptor reaches distal dendrites.

   Evidence Yeast two-hybrid screen plus GST pull-down from rat brain and transfected cells, with siRNA knockdown in primary neurons scoring receptor localization

   PMID:18685031

   Open questions at the time

   • Binding affinity and the precise receptor motif not yet quantified
   • Trafficking machinery recruited by YIF1B not identified
2. 2012 High

   Resolved the molecular basis of the interaction and defined YIF1B as a scaffold recruiting a motor/Rab vesicular complex, explaining the transport mechanism.

   Evidence Directed mutagenesis, GST pull-down, surface plasmon resonance (KD ≈ 37 nM), neuronal siRNA of each partner, and live videomicroscopy of co-trafficking vesicles

   PMID:23055492

   Open questions at the time

   • Stoichiometry and assembly order of the Yip1A/Rab6/Kif5B complex unresolved
   • Whether YIF1B couples cargo loading to motor activation not mechanistically dissected
3. 2015 High

   Localized YIF1B to the intermediate compartment and assigned it a directional, anterograde-specific trafficking role separable from its structural Golgi function.

   Evidence Fractionation/immunostaining, VSVG anterograde and Shiga toxin retrograde trafficking assays in HeLa cells and KO-mouse neurons, with EM of Golgi after short- versus long-term depletion

   PMID:26077767

   Open questions at the time

   • Molecular basis for the acceleration of VSVG transport upon depletion unexplained
   • How chronic loss leads to Golgi disorganization not defined
4. 2019 Medium

   Generalized YIF1B beyond serotonin receptors by showing it handles the ER-to-Golgi step of the lysosomal transporter TAPL through transmembrane-domain contacts.

   Evidence Co-IP/interactome, RUSH trafficking synchronization, confocal imaging, and TMD0 charged-residue mutagenesis

   PMID:30877195

   Open questions at the time

   • Interaction-domain detail derives from TAPL mutagenesis rather than YIF1B residues
   • Single-lab evidence without reciprocal structural validation
5. 2020 Medium

   Connected YIF1B trafficking function to organismal serotonergic physiology and behavior, establishing in vivo relevance.

   Evidence Yif1B KO mice with autoradiographic projection-fiber density, electrophysiology of 5-HT1A autoreceptors, and social-interaction/fluoxetine behavioral assays

   PMID:32459080

   Open questions at the time

   • Causal chain from receptor mistargeting to fiber-density loss not fully traced
   • Single-lab behavioral phenotyping
6. 2020 Medium

   Defined YIF1B as a disease gene whose loss couples ER/Golgi trafficking defects to ciliary abnormalities, broadening its cellular role.

   Evidence Biallelic LOF mutations in patients, KO mice and patient fibroblasts analyzed by ER/Golgi immunostaining, EM, and ciliary architecture

   PMID:33103737

   Open questions at the time

   • Mechanistic link between Golgi trafficking and ciliogenesis not established
   • YIF1B is absent from cilia, so the effect is indirect by an undefined route
7. 2024 Medium

   Showed YIF1B mediates unconventional secretion of a viral cargo, extending its anterograde role to pathogen-driven inflammation.

   Evidence Mass-spectrometry interactome, α4-helix/β8-sheet domain mapping, and knockdown in cell and hamster models with inflammation/mortality readouts

   PMID:39811650

   Open questions at the time

   • Whether ORF8 uses the same Yip1A/Rab6/Kif5B machinery unknown
   • Single-lab interactome without reciprocal binding validation

• How YIF1B selects and discriminates among its diverse cargo and how its trafficking activity mechanistically controls Golgi and ciliary integrity remains unresolved.
• No structural model of YIF1B or its cargo-binding interfaces
• Unifying mechanism linking anterograde transport, Golgi maintenance, and ciliogenesis absent
• Cargo selectivity rules across receptors, transporters, and viral proteins undefined