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Related Concept Videos

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:
The Ras Gene02:38

The Ras Gene

The Ras-gene-encoded proteins are regulators of signaling pathways controlling cell proliferation, differentiation, or cell survival. The Ras-gene family in humans constitutes three primary members—the HRas, NRas, and KRas. These genes code for four functionally distinct yet closely related proteins—the HRas, NRas, KRas4A, and KRas4B. The involvement of mutant Ras genes in human cancer was first discovered in 1982 and is among the most common causes of human tumorigenesis.
Ras is a superfamily...
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, also known...
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, also known...
Activation and Inactivation of G Proteins01:22

Activation and Inactivation of G Proteins

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 affinity and are together...
Rab Proteins01:14

Rab Proteins

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...

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Comparing the Affinity of GTPase-binding Proteins using Competition Assays
10:37

Comparing the Affinity of GTPase-binding Proteins using Competition Assays

Published on: October 8, 2015

Light on the structural communication in Ras GTPases.

Francesco Raimondi1, Angelo Felline, Guillem Portella

  • 1Department of Chemistry, University of Modena and Reggio Emilia, Modena, Italy.

Journal of Biomolecular Structure & Dynamics
|August 2, 2012
PubMed
Summary

Graph theory and fluctuation dynamics reveal how nucleotide binding creates structural networks in small G proteins. This nucleotide dependence is crucial for signal transfer, highlighting distinct communication paths in active versus inactive states.

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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

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Comparing the Affinity of GTPase-binding Proteins using Competition Assays
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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
10:27

Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells

Published on: March 9, 2012

Area of Science:

  • Biophysics
  • Structural Biology
  • Computational Biology

Background:

  • Small G proteins are crucial regulators of cellular processes.
  • Their function relies on nucleotide binding, which influences their structure and dynamics.
  • Understanding structural communication is key to deciphering their signaling mechanisms.

Purpose of the Study:

  • To investigate structural communication pathways in four small G proteins (Arf1, H-Ras, RhoA, Sec4) using graph theory and fluctuation dynamics.
  • To determine the role of nucleotide binding in establishing persistent structural networks and signal transfer.
  • To analyze differences in communication dynamics between inactive (GDP-bound) and active (GTP-bound) states.

Main Methods:

  • Application of graph theory to analyze protein structural networks.
  • Utilizing fluctuation dynamics to identify communication paths.
  • Comparative analysis of four small G proteins in both nucleotide-bound and unbound states.

Main Results:

  • Nucleotide binding is essential for forming persistent structural networks and high-frequency communication paths in small G proteins.
  • The Ras-like domain separates into two distinct lobes (N-terminal lobe 1 and C-terminal lobe 2) based on communication patterns.
  • Nucleotide-dependent structural communication varies significantly among Arf1, H-Ras, RhoA, and Sec4, with Arf1 showing maximum divergence.
  • Specific communication pathways differ between GDP- and GTP-bound states, particularly involving the G box 4 (G4) region.

Conclusions:

  • Small G proteins require nucleotide binding to effectively transfer signals through dynamic structural networks.
  • Distinct communication patterns between lobes and families are influenced by nucleotide state and may relate to membrane anchoring.
  • Arf1 exhibits unique nucleotide-dependent communication patterns compared to H-Ras, RhoA, and Sec4.