RAB41

RAB41 is a Golgi-resident Rab GTPase that maintains Golgi ribbon architecture and supports anterograde membrane trafficking, with a distinct stress-induced role in xenophagic clearance of intracellular bacteria (PMID:23936529, PMID:37802980). Under basal conditions it organizes the Golgi ribbon: depletion or expression of a GDP-locked mutant fragments the ribbon into clustered punctate elements with accumulating vesicles, partially blocks ER-to-Golgi transport of VSV-G, and inhibits cell growth, while acting in parallel with Rab6 (PMID:23936529). In its GTP-bound state RAB41 engages the dynactin subunit dynactin 6 and syntaxin 8, and loss of either partner reproduces the Golgi fragmentation phenotype, providing a molecular basis for RAB41-dependent recruitment of minus-end-directed motor machinery to the Golgi (PMID:26973836). RN-Tre serves as its GTPase-activating protein (PMID:16086013). Upon bacterial infection RAB41 relocalizes from the Golgi to pathogen-containing autophagic vesicles, whose formation depends on an intact RAB41-positive Golgi (PMID:29582580); on damaged autophagic membranes it is recruited via the adaptor TOM1L2 and, independently of its GTPase activity, recruits the AAA-ATPase VPS4 to drive ESCRT-mediated membrane repair, sustaining xenophagolysosome acidification and efficient bacterial clearance (PMID:37802980).

1. 2005 Medium

   Established that RAB41 has a dedicated regulator by reassigning RN-Tre, previously thought to act on Rab5, as the GAP for RAB41, defining how its GTP cycle is switched off.

   Evidence in vitro GAP activity and substrate specificity assays

   PMID:16086013

   Open questions at the time

   • No mutagenesis details or structural basis of GAP recognition provided
   • GEF and full regulatory cycle not defined
   • Cellular consequence of RN-Tre-mediated inactivation untested
2. 2013 High

   Defined RAB41's core cellular function by showing it is required for Golgi ribbon integrity and anterograde ER-to-Golgi transport, distinguishing it functionally from Rab6.

   Evidence siRNA knockdown, dominant-negative/constitutively-active mutant overexpression, EM, VSV-G transport assay, and double-knockdown epistasis in cultured cells

   PMID:23936529

   Open questions at the time

   • Effectors mediating the Golgi phenotype not identified in this study
   • Mechanism linking RAB41 to cell growth unresolved
   • Whether transport defect is direct or secondary to Golgi fragmentation unclear
3. 2016 High

   Identified RAB41 effectors, showing GTP-dependent binding to dynactin 6 and syntaxin 8 and providing a molecular mechanism — minus-end motor recruitment — for its Golgi ribbon role.

   Evidence yeast two-hybrid screen with GTP/GDP-locked mutant Co-IP validation and effector knockdown phenotyping

   PMID:26973836

   Open questions at the time

   • Direct demonstration of motor recruitment to Golgi membranes not shown
   • Stoichiometry and assembly of RAB41-dynactin complex undefined
   • Functional role of syntaxin 8 interaction not separately dissected
4. 2018 Medium

   Revealed a stress-induced relocalization program in which RAB41 moves from Golgi to bacteria-containing autophagic vesicles, linking Golgi integrity to anti-bacterial autophagy.

   Evidence fluorescence imaging of relocalization, Golgi disruption, ubiquitin-linkage analysis, and Nedd4-1 perturbation during S. pneumoniae infection

   PMID:29582580

   Open questions at the time

   • Mechanism driving RAB41 relocalization from Golgi not defined
   • Direct molecular role of RAB41 at PcAV not yet established here
   • Relationship between Nedd4-1 ubiquitination and RAB41 unclear
5. 2023 High

   Mechanistically resolved RAB41's anti-bacterial role, showing it is recruited to damaged autophagic membranes via TOM1L2 and recruits VPS4 for ESCRT-mediated repair in a GTPase-independent manner.

   Evidence Rab GTPase screen, confocal microscopy, intrabody inhibition of bacterial cytolysin, TOM1L2/VPS4 colocalization, GTPase-dead mutant analysis, and bacterial clearance assays

   PMID:37802980

   Open questions at the time

   • How TOM1L2 selects RAB41 in a GTPase-independent mode is unresolved
   • Structural basis of RAB41-VPS4 recruitment not defined
   • Whether basal Golgi role and repair role share regulators is untested

• How RAB41 switches between its GTP-dependent Golgi-organizing function and its GTPase-independent membrane-repair function, and what GEF activates it, remain unknown.
• No GEF identified for RAB41
• No structural model of RAB41 in either complex
• Trigger and trafficking route for Golgi-to-autophagosome relocalization undefined