Related Experiment Video
Updated: May 29, 2026
05:13
Density Gradient Ultracentrifugation for Investigating Endocytic Recycling in Mammalian Cells
Published on: June 30, 2021
RNF13 regulates the endolysosomal pathway through interaction with the small GTPase Arl8B
Audrey M Sénécal1,2,3, Valérie C Cabana1,2,3, Antoine Y Bouchard1,2,3
1Department of Chemistry, Université du Québec à Montréal, Canada.
The FEBS Journal
|May 28, 2026
Summary
The E3 ubiquitin ligase RNF13 regulates endolysosomal dynamics by binding to the GTPase Arl8B, influencing lysosome positioning and epidermal growth factor receptor (EGFR) trafficking to degradation pathways.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- The endolysosomal system is crucial for cellular waste disposal and recycling.
- Proper regulation of endosome maturation and positioning is vital for lysosomal function and receptor turnover.
- The small GTPase Arl8B plays a role in endolysosomal positioning and trafficking.
Purpose of the Study:
- To investigate the role of the E3 ubiquitin ligase RNF13 in endolysosomal dynamics.
- To identify potential interactions between RNF13 and components of the endolysosomal system, specifically Arl8B.
- To elucidate the functional consequences of the RNF13-Arl8B interaction on lysosomal organization and cargo trafficking.
Main Methods:
- Predictive structural modeling to predict binding interfaces.
- Co-immunoprecipitation assays to confirm RNF13-Arl8B interaction.
- Cell-based assays to assess the impact of disrupting RNF13-Arl8B binding on lysosomal localization and EGFR trafficking.
Main Results:
- RNF13 directly binds to Arl8B, with a preference for the GDP-bound state.
- Disruption of RNF13-Arl8B interaction alters Arl8B localization and causes lysosome redistribution to the cell periphery.
- Perturbing the interaction selectively delays epidermal growth factor receptor (EGFR) degradation without affecting general endocytosis.
- RNF13 influences Arl8B-dependent trafficking complexes and lysosomal organization.
Conclusions:
- RNF13 acts as a novel regulator of lysosomal positioning and endolysosomal cargo transport.
- The interaction between RNF13 and Arl8B provides a new regulatory mechanism for trafficking pathways.
- RNF13 highlights a regulatory node influencing cargo progression through degradative pathways via Arl8B binding and ubiquitination.
Related Concept Videos
01:45Regulation of Nuclear Protein Sorting
Nuclear protein sorting regulates nucleus composition and gene expression, crucial for determining the fate of a eukaryotic cell. Hence, the entry and exit of molecules across the nuclear envelope is a tightly controlled process. Nuclear protein sorting can be inhibited by one of the following ways: 1) masking cargo signal sequences, 2) modifying the nuclear receptor's affinity for cargo, 3) controlling the nuclear pore size, 4) retaining the cargo during its transit to the cytosol or the...
01:14Rab Proteins
Rab proteins constitute the largest family of monomeric GTPases, of which 70 members are present in humans. Rab proteins and their effectors regulate consecutive stages of vesicle transport such as vesicle transport, docking, and fusion to the correct recipient membrane.
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...
00:58Recycling Endosomes and Transcytosis
The recycling endosome, also known as the endosomal recycling compartment (ERC), is a part of the slow-recycling process of the endocytic pathway. Molecules internalized through receptor-mediated endocytosis are either degraded in the lysosomes or are recycled to the plasma membrane through the fast- or slow-recycling route.
The recycling endosome is not a single organelle but an extensively tubulated network of recycling pathways. It functions in storing molecules or transporting them across...
The recycling endosome is not a single organelle but an extensively tubulated network of recycling pathways. It functions in storing molecules or transporting them across...
01:25Rab Cascades
Rab GTPases act in a regulated cascade during membrane fusion, helping the lipid bilayers mix. The Rab family of proteins are active when bound to GTP, and inactive when bound to GDP. Hence, they act as guanine nucleotide-dependent molecular switches. Rab-GTP recognizes and binds to long or short-range tethering proteins to capture the target vesicle. These tethers coordinate with SNAREs on the vesicle and the target membrane to assemble the trans SNARE complex that locks the mixing bilayers.
01:42Directionality of Nuclear Transport
Ras-related nuclear protein or Ran is a small G protein that cycles between its GTP and GDP bound states. Ran specific regulators, a Ran GTPase Activating Protein or RanGAP present in the cytosol and a Ran guanine nucleotide exchange factor or RanGEF present inside the nucleus regulate GTP/GDP exchange. A high concentration of GTP inside the cells, in addition to this asymmetric distribution of Ran-specific regulators, leads to a higher RanGTP concentration inside the nucleus. This...
01:34Directing Proteins to the Rough Endoplasmic Reticulum
The organelle-specific signaling sequences direct proteins synthesized in the cytosol to their final destination like ER, mitochondria, peroxisomes, etc. Some of the proteins directed to ER are then trafficked via vesicles to other organelles within the cell or the extracellular environment through the Golgi complex. For example, the rough ER synthesizes soluble proteins for transportation to the lysosomes or secretion out of the cell. It can also synthesize transmembrane proteins that can...