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Related Concept Videos

GTPases and their Regulation02:14

GTPases and their Regulation

10.3K
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,...
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GTPases and their Regulation02:14

GTPases and their Regulation

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Small GTPases - Ras and Rho01:24

Small GTPases - Ras and Rho

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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:
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Activation and Inactivation of G Proteins01:22

Activation and Inactivation of G Proteins

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Heterotrimeric G proteins are guanine nucleotide-binding proteins. As the name suggests, heterotrimeric G proteins are composed of three subunits: alpha, beta, and gamma. They remain GDP-bound or GTP-bound inside the cells and switch between inactive/active states. The Gα subunit possesses the nucleotide-binding pocket that binds guanine nucleotides and switches between GDP or GTP-bound states. In contrast, the Gꞵ and Gγ subunits are always bound together with high...
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Rab Proteins01:14

Rab Proteins

5.4K
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...
5.4K
Rab Cascades01:25

Rab Cascades

3.7K
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.
3.7K

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Related Experiment Video

Updated: Mar 23, 2026

Comparing the Affinity of GTPase-binding Proteins using Competition Assays
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Comparing the Affinity of GTPase-binding Proteins using Competition Assays

Published on: October 8, 2015

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Are There Rab GTPases in Archaea?

Jaroslaw Surkont1, Jose B Pereira-Leal2

  • 1Instituto Gulbenkian de Ciencia, Oeiras, Portugal jsurkont@igc.gulbenkian.pt.

Molecular Biology and Evolution
|April 2, 2016
PubMed
Summary

The Rab family of small GTPases, crucial for vesicle trafficking in eukaryotes, likely originated in Archaea before the emergence of eukaryotes. This discovery supports the archaeal ancestry of eukaryotes and sheds light on early membrane signaling evolution.

Keywords:
LECALokiarchaeumRasendomembrane trafficking systemeukaryogenesisprotein prenylation.

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

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Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells
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Detection of Small GTPase Prenylation and GTP Binding Using Membrane Fractionation and GTPase-linked Immunosorbent Assay
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Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells
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Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells

Published on: March 9, 2012

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Area of Science:

  • Molecular Biology
  • Evolutionary Biology
  • Cell Biology

Background:

  • Eukaryotic vesicle trafficking relies on Rab GTPases for compartment identity and specificity.
  • The evolutionary origin of the diverse Rab GTPase repertoire remains unclear.
  • The discovery of eukaryotic-like systems, including small GTPases, in Lokiarchaeota suggests ancient archaeal origins.

Purpose of the Study:

  • To test the hypothesis that the Rab family of small GTPases predates the origin of Eukaryotes.
  • To investigate the evolutionary history of Rab GTPases and their regulatory proteins.
  • To provide insights into the archaeal ancestry of eukaryotic cellular machinery.

Main Methods:

  • Bioinformatic analysis of archaeal genomes to identify Rab-like proteins.
  • Sequence analysis to detect conserved Rab family motifs.
  • Structure-based methods to identify Rab Escort Protein/GDP dissociation Inhibitor (REP/GDI)-like genes in Archaea.

Main Results:

  • Multiple putative Rab-like proteins were identified in various archaeal species.
  • Conserved sequence features distinguishing eukaryotic Rabs were found in archaeal homologs.
  • Archaeal REP/GDI-like genes involved in isoprenyl metabolism were discovered.

Conclusions:

  • The Rab family of small GTPases likely differentiated within Archaea prior to eukaryotic evolution.
  • These findings support the archaeal origin of the eukaryotic ancestor.
  • The study illuminates intermediate evolutionary stages of complex membrane-associated signaling circuits.