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Analysis of Endocytic Uptake and Retrograde Transport to the Trans-Golgi Network Using Functionalized Nanobodies in Cultured Cells
Published on: February 21, 2019
Rab15 differentially regulates early endocytic trafficking
1Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202, USA.
The Journal of Biological Chemistry
|June 6, 2000
Summary
Rab15 (HArab15) regulates early endocytosis by controlling early endosome fusion. Active Rab15 inhibits endocytosis, while inactive forms stimulate it, suggesting a counteracting role to Rab5 in membrane trafficking.
Area of Science:
- Cell biology
- Molecular biology
- Membrane trafficking
Background:
- Rab GTPases are key regulators of intracellular membrane trafficking.
- Rab15 (HArab15) localizes to early endosomal membranes.
- Understanding Rab15's role in endocytosis is crucial for deciphering cellular transport.
Purpose of the Study:
- To characterize the function of Rab15 in endocytosis using functional mutants.
- To investigate Rab15's influence on early endocytic trafficking and fusion events.
- To determine Rab15's interaction with Rab5 in regulating endocytosis.
Main Methods:
- Preparation and analysis of functional Rab15 mutants (wild-type, Q67L, T22N, N121I).
- Assessment of fluid phase and receptor-mediated endocytosis rates.
- In vitro assays for homotypic early endosome fusion.
- Examination of Rab5-stimulated endocytosis in cells overexpressing Rab15 mutants.
Main Results:
- Active Rab15 (Q67L) inhibits early endocytosis and homotypic fusion.
- Inactive Rab15 mutants stimulate early endocytosis and fusion.
- Inactive Rab15 mutants differentially affect endocytic tracer transit and recycling.
- Active Rab15 attenuates Rab5-stimulated endocytosis, while inactive Rab15 augments it.
Conclusions:
- Rab15 plays a regulatory role in early endocytosis, potentially counteracting Rab5.
- Rab15 differentially regulates membrane trafficking steps through early/sorting and recycling endosomes.
- Functional states of Rab15 (active vs. inactive) have distinct effects on endocytic pathways.
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