Ras-related protein Rab-1B
Function
The small GTPases Rab are key regulators of intracellular membrane trafficking, from the formation of transport vesicles to their fusion with membranes (PubMed:20545908, PubMed:9437002). Rabs cycle between an inactive GDP-bound form and an active GTP-bound form that is able to recruit to membranes different set of downstream effectors directly responsible for vesicle formation, movement, tethering and fusion (PubMed:9437002). Plays a role in the initial events of the autophagic vacuole development which take place at specialized regions of the endoplasmic reticulum (PubMed:20545908). Regulates vesicular transport between the endoplasmic reticulum and successive Golgi compartments (By similarity). Required to modulate the compacted morphology of the Golgi (PubMed:26209634). Promotes the recruitment of lipid phosphatase MTMR6 to the endoplasmic reticulum-Golgi intermediate compartment (By similarity).
Post-translational modifications
Prenylated; by GGTase II, only after interaction of the substrate with Rab escort protein 1 (REP1).
(Microbial infection) AMPylation at Tyr-77 by L.pneumophila DrrA occurs in the switch 2 region and leads to moderate inactivation of the GTPase activity. It appears to prolong the lifetime of the GTP state of RAB1B by restricting access of GTPase effectors to switch 2 and blocking effector-stimulated GTP hydrolysis, thereby rendering RAB1B constitutively active. It is later de-AMPylated by L.pneumophila SidD, releasing RAB1B from bacterial phagosomes.
(Microbial infection) Phosphocholinated at Ser-76 by L.pneumophila AnkX, leading to displace GDP dissociation inhibitors (GDI) (PubMed:21822290, PubMed:22307087). Both GDP-bound and GTP-bound forms can be phosphocholinated. Dephosphocholinated by L.pneumophila Lem3, restoring accessibility to L.pneumophila GTPase effector LepB (PubMed:22158903, PubMed:22307087).
(Microbial infection) Glycosylated by S.typhimurium protein Ssek3: arginine GlcNAcylation prevents GTPase activity, thereby disrupting vesicular protein transport from the endoplasmic reticulum (ER) to the Golgi compartment.
Sequence Similarities
Belongs to the small GTPase superfamily. Rab family.
Cellular localization
- Cytoplasm
- Membrane
- Lipid-anchor
- Cytoplasmic side
- Preautophagosomal structure membrane
- Lipid-anchor
- Cytoplasmic side
- Cytoplasm
- Perinuclear region
- Targeted by REP1 to membranes of specific subcellular compartments including endoplasmic reticulum, Golgi apparatus, and intermediate vesicles between these two compartments (PubMed:11389151). In the GDP-form, colocalizes with GDI in the cytoplasm (PubMed:11389151). Co-localizes with MTMR6 to the endoplasmic reticulum-Golgi intermediate compartment and to the peri-Golgi region (By similarity).
Alternative names
Ras-related protein Rab-1B, RAB1B