| 1995 |
Rabin3 (RAB3IP) was identified as a novel protein that interacts specifically with Rab3A and Rab3D (but not Rab3C, Rab2, Ran, or Ras) via the effector domain of Rab3A; point mutations F51L, V55E, and G56D in the effector domain of Rab3A abolish the interaction. The protein contains a region of sequence similarity to the yeast Sec2p GEF. However, in vitro the GST-Rabin3 fusion protein associates only weakly with recombinant Rab3A and possesses no detectable GTPase-activating protein or nucleotide exchange activity toward Rab3A. |
Yeast two-hybrid screen, GST pulldown, in vitro GTPase assays, point mutagenesis |
Molecular and cellular biology |
Medium |
7532276
|
| 2002 |
RAB3IP (human Rabin3/Rabin8) physically interacts with the cancer-related protein SSX2 in vitro and in cells. GST pulldown confirmed direct interaction. Co-expression of RAB3IP and SSX2 causes relocalization of the normally cytoplasmic RAB3IP to the nucleus. The interaction maps to the N-terminal moiety of SSX2, and RAB3IP does not interact with SSX1, SSX3, or SSX4. |
Yeast two-hybrid, GST pulldown, immunofluorescence co-localization in transfected cells |
Genes, chromosomes & cancer |
Medium |
12007189
|
| 2005 |
Rabin8 (human) and its rat equivalent Rabin3 function as guanine nucleotide exchange factors (GEFs) specifically for Rab8 but not for Rab3A or Rab5. Endogenous and ectopically expressed Rabin8 colocalizes with cortical actin; cytochalasin D and phorbol esters induce translocation of both Rabin8 and Rab8 to lamellipodia-like structures. Co-expression of Rabin8 with dominant-negative Rab8 causes relocalization of Rabin8 to vesicular structures enriched in cell protrusions, implicating both proteins in polarized membrane transport. |
In vitro nucleotide exchange assay, live cell imaging, co-expression of dominant-negative Rab8, fluorescence microscopy |
Methods in enzymology |
Medium |
16473595
|
| 2011 |
Upon serum withdrawal, Rabin8 relocalizes to Rab11-positive vesicles that are transported to the centrosome to initiate ciliogenesis. Rab11-GTP associates with the Rabin8 C-terminal region and this interaction is required for Rabin8 preciliary membrane trafficking to the centrosome and for ciliogenesis. The TRAPPII complex associates with the Rabin8 N-terminal domain and TRAPPII subunits colocalize with centrosomal Rabin8 and are required for Rabin8 preciliary targeting and ciliogenesis. The BBSome binds Rabin8, which acts as a GEF activating Rab8 for ciliary membrane formation. |
Live fluorescence microscopy, tandem affinity purification/mass spectrometry, zebrafish epistasis, co-IP, dominant-negative and knockdown experiments |
Proceedings of the National Academy of Sciences of the United States of America |
High |
21273506
|
| 2011 |
Rabin8 co-immunoprecipitates with the GTPase Rheb. Overexpression of Rabin8 suppresses phosphorylation of Ser235/Ser236 in ribosomal protein S6 (a readout of mTORC1 activity), while siRNA-mediated knockdown of Rabin8 increases this phosphorylation, indicating Rabin8 negatively regulates mTORC1 signaling. |
Co-immunoprecipitation, siRNA knockdown, Western blotting for pS6 |
Acta naturae |
Low |
22649696
|
| 2012 |
NDR1/2 kinases phosphorylate Rabin8 in brain neurons, as identified by chemical genetics (analog-sensitive kinase allele). Rabin8, as an NDR1/2 substrate, regulates dendritic spine development; knockdown or dominant-negative NDR1/2 affects spine morphology, a phenotype linked to Rabin8 activity as a Rab8 GEF. |
Chemical genetic substrate identification (analog-sensitive NDR1/2), mass spectrometry, siRNA knockdown, dominant-negative expression, in vivo neuron imaging |
Neuron |
High |
22445341
|
| 2013 |
NDR2 phosphorylates Rabin8 at Ser-272. This phosphorylation is crucial for ciliogenesis: the non-phosphorylatable S272A mutant causes accumulation of Rabin8/Rab11-containing vesicles at the pericentrosome and impairs preciliary membrane assembly. Mechanistically, Rabin8 binds GTP-bound Rab11 and phosphatidylserine (PS) on pericentrosomal vesicles; the phospho-mimetic S272E mutation decreases affinity for PS but increases affinity for the exocyst component Sec15. Thus NDR2-mediated phosphorylation switches Rabin8 binding specificity from PS to Sec15 to promote Rab8 activation and ciliary membrane formation. |
In vitro kinase assay, phospho-mimetic and non-phosphorylatable Rabin8 mutants, binding assays (lipid and protein), immunofluorescence, ciliogenesis assays |
The EMBO journal |
High |
23435566
|
| 2013 |
Structural snapshots of the full Rabin8-catalyzed nucleotide exchange reaction for Rab8 were obtained, revealing three distinct enzyme-substrate complexes: Rab8·Rabin8·GDP (ternary), nucleotide-free Rab8·Rabin8 (binary), and Rab8·Rabin8·GTP (ternary product). Enzymatic characterization provided a mechanistic model for Rabin8/GRAB-mediated GEF activity. |
Structural analysis (crystal snapshots), in vitro enzymatic characterization of nucleotide exchange |
The Journal of biological chemistry |
High |
24072714
|
| 2015 |
Rabin8 suppresses autophagosome formation independently of its Rab8-GEF activity: depletion of Rabin8 promotes nutrient starvation-induced autophagosome formation, and a Rabin8 GEF-domain mutant (lacking GEF activity) still rescues this phenotype, while depletion of Rab8 does not affect autophagosome formation. NDR kinase-dependent phosphorylation of Rabin8 at Ser-272 is involved in this suppressive function (non-phosphorylatable S272A fails to rescue). Rabin8's suppressive function in autophagy requires its non-conserved C-terminal region. |
siRNA knockdown, GEF-dead mutant expression, non-phosphorylatable mutant rescue assays, autophagosome quantification by microscopy and Western blot |
Journal of biochemistry |
Medium |
25787272
|
| 2015 |
The Arf/Rab11 effector FIP3 (RAB11FIP3) coordinates the interactions of ASAP1 and Rab11a with Rabin8 within a targeting complex for ciliary receptor (rhodopsin) trafficking. FIP3 competes with rhodopsin for binding to ASAP1 and shapes the binding pocket for Rabin8 within the ASAP1-Rab11a-FIP3 complex, facilitating assembly and activation of the Rab11-Rabin8-Rab8 cascade during ciliary receptor trafficking. |
Co-immunoprecipitation, siRNA ablation of FIP3 with rhodopsin mislocalization readout, epistasis in photoreceptor cells |
Journal of cell science |
Medium |
25673879
|
| 2019 |
TRAPPC14 (C7orf43/MAP11), a newly identified TRAPPII-specific subunit, directly binds Rabin8 and mediates Rabin8 association with the TRAPPII complex. TRAPPC14 knockdown diminishes Rabin8 preciliary centrosome accumulation. TRAPPC14 also interacts with distal appendage proteins FBF1 and CEP83, which are required for GFP-Rabin8 centrosomal accumulation, supporting a role for the TRAPPII complex in tethering preciliary vesicles containing Rabin8 to the mother centriole. |
MS-based interactome identification, co-sedimentation, direct binding assays, siRNA knockdown with ciliogenesis and localization readouts, zebrafish validation |
The Journal of biological chemistry |
High |
31467083
|
| 2019 |
Phosphorylation of Rab8a at Ser111 (by PINK1 kinase) impairs Rabin8-mediated nucleotide exchange. Mechanistically, pS111 (or the phosphomimetic S111E) establishes an intramolecular interaction with Arg79 in Rab8a, which disrupts a key intermolecular salt bridge between Rab8a Arg79 and Rabin8 Asp187, drastically reducing binding affinity and nucleotide exchange rate (>80% decrease confirmed in vitro). |
Molecular dynamics simulations, free energy calculations, in vitro nucleotide exchange assay with Rab8a mutants |
Biochemistry |
Medium |
31361120
|
| 2020 |
In C. elegans, RABN-8 (Rabin8 ortholog), as a GEF for RAB-8, is required for vulval tumor formation caused by hyperactivated EGFR signaling. Mechanistically, RABN-8 promotes secretion of EGL-17/FGF from vulval precursor cells, connecting the Rab8-Rabin8 trafficking axis to FGF-mediated signaling downstream of EGFR. |
RNAi knockdown in C. elegans multivulva model, genetic epistasis, FGFR inhibitor rescue |
International journal of molecular sciences |
Medium |
33092268
|
| 2023 |
CENTLEIN directly binds RABIN8, with a 31-amino acid sequence in the 200–230 region of the RABIN8 GEF domain mediating the interaction. CENTLEIN depletion causes persistent accumulation of RABIN8 at the pericentrosome and primary cilium loss. Expression of full-length but not RABIN8-binding-deficient CENTLEIN rescues the ciliogenesis defect. Expression of activated RAB8A partially reverses cilium loss in CENTLEIN-null cells, placing CENTLEIN upstream of Rabin8-mediated Rab8 activation in ciliogenesis. |
Direct binding assay with deletion mapping, siRNA/CRISPR knockdown/knockout, rescue with full-length vs. deletion mutant CENTLEIN, activated RAB8A epistasis |
Acta biochimica et biophysica Sinica |
Medium |
37475549
|
| 2024 |
Rabin8 acts as the guanine exchange factor activating Rab8 downstream of low-affinity LFA1-dependent outside-in signaling in lymphocytes. Rabin8-mediated Rab8 activation at the cell contact area drives intracellular transport and accumulation of LFA1-containing vesicles at the contact surface, modulating LFA1 avidity (increased frequency of LFA1-ICAM1 interactions without affecting binding lifetime) independent of Rap1. |
Super-resolution microscopy, single-molecule imaging on supported lipid bilayers, Rab8 inactivation, live cell imaging |
PNAS nexus |
Medium |
39170909
|
| 2025 |
In Xenopus laevis transgenic rod photoreceptors, Rabin8 accumulates at Golgi exit sites (GESs)/trans-Golgi network and is integrated into rhodopsin transport carriers (RTCs) following NDR2-mediated phosphorylation at S272. Rabin8 mutants deficient in Rab11 binding prevent membrane association. Both GFP-Rabin8 and NDR2 kinase interact with the RTC-associated R-SNARE VAMP7 at the trans-Golgi and GESs. The phosphomimetic S272E mutant integrates into RTCs and supports subsequent Rab8 GEF activity, while the non-phosphorylatable S272A mutant causes GES enlargement and deformation and abnormal membrane advancement, bypassing RTCs—establishing that NDR2 phosphorylation of Rabin8 regulates Rab11-to-Rab8 succession in rhodopsin Golgi-to-cilia trafficking. |
Xenopus laevis transgenic photoreceptors expressing GFP-Rabin8 wild-type and mutants, co-immunoprecipitation with VAMP7, confocal and electron microscopy, phospho-mimetic and non-phosphorylatable mutant analysis |
Journal of cell science |
High |
39774853
|
| 2025 |
In C. elegans, RABI-1 (Rabin8 ortholog) and RAB-11.2 mediate secondary dendrite branch elimination downstream of the NDR kinase SAX-1 during stress-induced neuronal remodeling. SAX-1 promotes endocytosis during remodeling, and RABI-1/RAB-11.2 effects on tertiary branch elimination are minimal, revealing branch-specific mechanistic requirements. |
C. elegans genetic epistasis, RNAi/mutant analysis, dendrite pruning quantification, endocytosis assays |
bioRxivpreprint |
Medium |
bio_10.1101_2025.06.09.658633
|