Related Experiment Video

Updated: Sep 28, 2025

High-throughput Measurement of Dictyostelium discoideum Macropinocytosis by Flow Cytometry
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High-throughput Measurement of Dictyostelium discoideum Macropinocytosis by Flow Cytometry

Published on: September 10, 2018

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The PripA-TbcrA complex-centered Rab GAP cascade facilitates macropinosome maturation in Dictyostelium

Hui Tu1,2, Zhimeng Wang1,2, Ye Yuan1,2

  • 1National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China.

Nature Communications
|April 5, 2022
PubMed

Insights

Researchers discovered a protein complex, PripA-TbcrA, crucial for macropinosome maturation. This complex facilitates the switch from Rab5 to Rab7, ensuring efficient cargo processing during fluid uptake.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Macropinocytosis is a cellular process for bulk fluid uptake with diverse functions.
  • The maturation pathway of macropinosomes, particularly the Rab5-to-Rab7 transition, is not well understood.

Purpose of the Study:

  • To identify proteins involved in macropinosome maturation during the Rab5-to-Rab7 transition.
  • To elucidate the mechanism of Rab5 inactivation and Rab7 activation in macropinosome maturation.

Main Methods:

  • Proteomic analysis of macropinosomes during the Rab5-to-Rab7 transition in Dictyostelium.
  • Biochemical assays to study protein interactions and Rab GTPase activity.
  • Genetic disruption of identified proteins (pripA, tbcrA) to assess functional consequences.

Main Results:

  • A novel complex of PripA and TbcrA was identified on macropinosomes.
  • PripA bridges early (Rab5) and late (Rab7) macropinosomes via PI(3,4)P2 and Rab7 interactions.
  • PripA recruits TbcrA, a Rab5 GTPase-activating protein (GAP), leading to Rab5 inactivation.
  • Disruption of PripA or TbcrA impairs Rab5 inactivation and macropinocytic cargo processing.

Conclusions:

  • The PripA-TbcrA complex is essential for programmed Rab switching during macropinosome maturation.
  • This complex acts as a Rab GAP cascade, linking Rab5 inactivation to Rab7 engagement.
  • Efficient macropinocytic cargo trafficking relies on this PripA-TbcrA-mediated maturation process.

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