Related Experiment Video

Updated: Aug 4, 2026

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

Global conformational rearrangements during the activation of the GDP/GTP exchange factor Vav3

Oscar Llorca1, Ernesto Arias-Palomo, José L Zugaza

  • 1Centro de Investigaciones Biológicas, CSIC, Madrid, Spain.

The EMBO Journal
|March 19, 2005
PubMed

Insights

The study reveals how Vav3, a key signaling protein, changes shape upon activation. Understanding these structural shifts in GDP/GTP exchange factors is crucial for cell signaling research.

Area of Science:

  • Cellular signaling pathways
  • Molecular and structural biology
  • Protein dynamics and regulation

Background:

  • Rho/Rac GTPases are critical for cell signaling and require Dbl family GDP/GTP exchange factors for activation.
  • While the catalytic core of Dbl proteins is understood, the structural dynamics of full-length proteins during activation remain largely unknown.
  • Vav3 is a key exchange factor involved in various cellular processes.

Purpose of the Study:

  • To elucidate the structural changes in the full-length Vav3 protein upon activation.
  • To compare the structures of inactive, active (phosphorylated), and constitutively active (N-terminally deleted) Vav3.
  • To understand the molecular mechanisms underlying Vav3 activation and constitutive activity.

Main Methods:

  • Single-particle electron microscopy (cryo-EM) was employed to determine high-resolution structures.
  • Structures of three distinct Vav3 states were solved: inactive (unphosphorylated), active (phosphorylated), and constitutively active (N-terminally deleted).
  • Comparative structural analysis was performed to identify interdomain interactions and conformational changes.

Main Results:

  • The study identified specific interdomain interactions that maintain Vav3 in its inactive, unphosphorylated state.
  • Dynamic structural changes in Vav3 upon tyrosine phosphorylation were revealed.
  • Distinct conformations were observed between phosphorylated Vav3 and N-terminally deleted Vav3, suggesting complexity beyond simple removal of inhibitory interactions.

Conclusions:

  • Tyrosine phosphorylation induces significant conformational rearrangements in Vav3, transitioning it to an active state.
  • The acquisition of constitutive activity in exchange factors is structurally more intricate than previously thought, involving more than just the elimination of inhibitory domain interactions.
  • These findings provide critical insights into the regulation of Dbl family exchange factors and their role in cell signaling.

More Related Videos

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

Single-Molecule FRET Imaging for Observing the Conformational Dynamics of Dynamin-Like GTPase Atlastin10:19

Single-Molecule FRET Imaging for Observing the Conformational Dynamics of Dynamin-Like GTPase Atlastin

Published on: January 24, 2025

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, also known...
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...
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...
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...
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:
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...