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Actin-based motility during endocytosis in budding yeast
Kyoungtae Kim1, Brian J Galletta, Kevin O Schmidt
1Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
Molecular Biology of the Cell
|January 6, 2006
Summary
Capping protein is crucial for early endocytic vesicle movement, supporting the dendritic nucleation model. Later endosome transport relies on different factors, highlighting distinct molecular needs in endocytosis.
Area of Science:
- Cell Biology
- Molecular Biology
- Biophysics
Background:
- Actin assembly nucleation by the Arp2/3 complex is vital for endocytic vesicle formation and movement.
- The dendritic nucleation model describes Arp2/3-mediated actin assembly and vesicle motility.
Purpose of the Study:
- To investigate the role of capping protein in Arp2/3-mediated actin assembly during yeast endocytosis.
- To quantitatively analyze the impact of capping protein on different stages of endocytic vesicle movement in vivo.
Main Methods:
- Quantitative tracking analysis of fluorescence markers for endocytosis stages in yeast.
- In vivo examination of capping protein function in the context of the dendritic nucleation model.
Main Results:
- Capping protein is essential for the initial movement and release of endocytic vesicles from the plasma membrane.
- Subsequent endosome movement away from the plasma membrane is also affected by capping protein, but to a lesser extent.
- Late-stage endocytic vesicle transport to the vacuole is independent of capping protein, relying instead on Lsb6.
Conclusions:
- Capping protein plays a key role in efficient actin assembly and force generation during early endocytosis, consistent with the dendritic nucleation model.
- The molecular machinery for Arp2/3-based actin assembly differs between early and late stages of the endocytic pathway.
- Disruption of actin cables increases the motility of endocytic patches.