Related Experiment Video

Updated: Jan 26, 2026

High-throughput Measurement of Dictyostelium discoideum Macropinocytosis by Flow Cytometry
06:47

High-throughput Measurement of Dictyostelium discoideum Macropinocytosis by Flow Cytometry

Published on: September 10, 2018

8.1K

Function of small GTPases in Dictyostelium macropinocytosis

Thomas D Williams1, Peggy I Paschke1, Robert R Kay1

  • 1MRC-Laboratory of Molecular Biology , Francis Crick Avenue, Cambridge CB2 0QH , UK.

Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
|April 11, 2019
PubMed

Insights

Dictyostelium discoideum uses macropinocytosis for nutrient uptake. Persistent Ras activation stimulates this process, with RasG and RasS identified as key Ras proteins involved in cellular fluid uptake.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Macropinocytosis is a cellular process for large-scale fluid uptake, crucial for nutrient acquisition in organisms like Dictyostelium discoideum.
  • This process involves the formation of membrane ruffles dependent on phosphatidylinositol (3,4,5)-trisphosphate (PIP3) and activated small G-proteins Ras and Rac.
  • While PIP3's requirement for macropinocytosis is established, the specific roles of Ras and Rac proteins remain less understood.

Purpose of the Study:

  • To investigate the roles of Ras and Rac proteins in Dictyostelium discoideum macropinocytosis.
  • To identify specific Ras proteins and guanine nucleotide exchange factors (GEFs) involved in regulating macropinocytosis.
  • To explore the relationship between PIP3 signaling and the activation of Rho family proteins in this cellular process.

Main Methods:

  • Utilized gain-of-function experiments to assess the impact of persistent Ras activation on macropinocytosis.
  • Conducted genetic analysis to identify key Ras proteins and implicated guanine nucleotide exchange factors (GEFs).
  • Investigated the activation mechanisms of Rho family proteins in relation to PIP3 signaling.

Main Results:

  • Persistent Ras activation was found to significantly stimulate macropinocytosis in Dictyostelium discoideum.
  • Genetic analysis identified RasG and RasS as the primary Ras proteins mediating this stimulation.
  • The guanine nucleotide exchange factor GefF was implicated in macropinocytosis through insertional mutant studies.
  • Evidence suggests that the activation of some Rho family proteins may occur independently of PIP3.

Conclusions:

  • Ras proteins, particularly RasG and RasS, play a crucial role in stimulating macropinocytosis in Dictyostelium discoideum.
  • GefF is identified as a key GEF involved in the macropinocytosis pathway.
  • The findings highlight a complex interplay between Ras/Rac signaling, GEFs, and PIP3 in regulating cellular nutrient uptake via macropinocytosis.
Keywords:
Dictyostelium discoideumRacRasendocytosismacropinocytosissmall G-protein

More Related Videos

Investigating the Function of Coronin A in the Early Starvation Response of Dictyostelium discoideum by Aggregation Assays07:48

Investigating the Function of Coronin A in the Early Starvation Response of Dictyostelium discoideum by Aggregation Assays

Published on: June 18, 2016

7.5K
Detection of Small GTPase Prenylation and GTP Binding Using Membrane Fractionation and GTPase-linked Immunosorbent Assay13:51

Detection of Small GTPase Prenylation and GTP Binding Using Membrane Fractionation and GTPase-linked Immunosorbent Assay

Published on: November 11, 2018

10.3K

Related Concept Videos

GTPases and their Regulation02:14

GTPases and their Regulation

Guanine nucleotide-binding proteins (G-proteins), also known as GTPases, are a superfamily of proteins that regulate many cellular processes, such as cell signaling, vesicular transport, and the regulation of cell shape and motility. Mutation or dysfunction of these proteins can lead to disease. There are around 40,000 known G-proteins that can broadly be classified into two groups ‒  small G-proteins consisting of a single domain and large multi-domain G-proteins.
Large G-proteins,...
9.8K
GTPases and their Regulation02:14

GTPases and their Regulation

2.9K
Small GTPases - Ras and Rho01:24

Small GTPases - Ras and Rho

Ras and Rho are small monomeric GTPases that act downstream of receptor tyrosine kinase (RTK) and regulate various cellular processes. These GTPases switch between active and inactive states by binding to guanine nucleotides.
Three regulatory proteins control their activity:
5.2K
Coat Assembly and GTPases01:33

Coat Assembly and GTPases

Vesicles incorporate different coat protein subunits in different cell locations, which changes the properties of the coat, such as the shape and geometry of the transport vesicles. Thus, vesicle coat proteins also play a significant role in cargo selection.
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
4.3K
Mechanical Protein Functions01:58

Mechanical Protein Functions

Proteins perform many mechanical functions in a cell. These proteins can be classified into two general categories- proteins that generate mechanical forces and proteins that are subjected to mechanical forces. Proteins providing mechanical support to the structure of the cell, such as keratin, are subjected to mechanical force, whereas proteins involved in cell movement and transport of molecules across cell membranes, such as an ion pump, are examples of generating mechanical force. 
5.5K
Functional Groups02:45

Functional Groups

Functional groups are a group of atoms with characteristic properties, which when linked to the carbon skeleton of a molecule, alter the properties of that molecule. For example, the presence of certain functional groups on a molecule will make them hydrophilic, whereas others will make them hydrophobic. These functional groups are an indispensable part of organic chemistry and important components of biological molecules, such as carbohydrates, proteins, lipids, and nucleic acids. Each...
88.0K