Related Experiment Video

Updated: Jul 23, 2026

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

Ras-activated endocytosis is mediated by the Rab5 guanine nucleotide exchange activity of RIN1

G G Tall1, M A Barbieri, P D Stahl

  • 1Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas 75390, USA.

Developmental Cell
|November 13, 2001
PubMed

Insights

Ras-activated protein RIN1 facilitates endocytosis by regulating Rab5 guanine nucleotide exchange. Activated Ras enhances RIN1

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Biochemistry

Background:

  • RIN1 protein identified for Ras inhibition, interacts with c-ABL and 14-3-3 proteins.
  • RIN1 possesses a Vps9p-like domain, characteristic of Rab guanine nucleotide exchange factors (GEFs).

Purpose of the Study:

  • To investigate RIN1's interaction with GDP-bound Rabs, specifically Vps21p and Rab5A.
  • To determine RIN1's role in stimulating Rab5 nucleotide exchange, endosome fusion, and EGF receptor-mediated endocytosis.
  • To elucidate the potentiation of RIN1's function by activated Ras.

Main Methods:

  • Protein interaction assays to confirm binding of RIN1 to GDP-bound Rabs.
  • Guanine nucleotide exchange assays to measure Rab5 activity.
  • Endocytosis assays measuring EGF receptor-mediated uptake.
  • Experiments assessing the effect of activated Ras on RIN1 function.

Main Results:

  • The Vps9p-like domain of RIN1 is essential and sufficient for binding GDP-bound Vps21p and Rab5A.
  • RIN1 stimulates Rab5 guanine nucleotide exchange, Rab5A-dependent endosome fusion, and EGF receptor endocytosis.
  • Activated Ras significantly potentiates RIN1's stimulatory effects on these processes.
  • Ras directly enhances the Rab5 nucleotide exchange activity of RIN1.

Conclusions:

  • RIN1 acts as a Rab GEF, mediating interactions with Vps21p and Rab5A.
  • RIN1 plays a crucial role in endocytosis, particularly EGF receptor trafficking.
  • Ras directly regulates RIN1's GEF activity, linking Ras signaling to endocytic pathways.

More Related Videos

Affinity Precipitation of Active Rho-GEFs Using a GST-tagged Mutant Rho Protein (GST-RhoA(G17A)) from Epithelial Cell Lysates11:28

Affinity Precipitation of Active Rho-GEFs Using a GST-tagged Mutant Rho Protein (GST-RhoA(G17A)) from Epithelial Cell Lysates

Published on: March 31, 2012

Imaging FITC-dextran as a Reporter for Regulated Exocytosis04:50

Imaging FITC-dextran as a Reporter for Regulated Exocytosis

Published on: June 20, 2018

Related Concept Videos

Recycling Endosomes and Transcytosis00:58

Recycling Endosomes and Transcytosis

The recycling endosome, also known as the endosomal recycling compartment (ERC), is a part of the slow-recycling process of the endocytic pathway. Molecules internalized through receptor-mediated endocytosis are either degraded in the lysosomes or are recycled to the plasma membrane through the fast- or slow-recycling route.
The recycling endosome is not a single organelle but an extensively tubulated network of recycling pathways. It functions in storing molecules or transporting them across...
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...
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...
Directing Proteins to the Rough Endoplasmic Reticulum01:34

Directing Proteins to the Rough Endoplasmic Reticulum

The organelle-specific signaling sequences direct proteins synthesized in the cytosol to their final destination like ER, mitochondria, peroxisomes, etc. Some of the proteins directed to ER are then trafficked via vesicles to other organelles within the cell or the extracellular environment through the Golgi complex. For example, the rough ER synthesizes soluble proteins for transportation to the lysosomes or secretion out of the cell. It can also synthesize transmembrane proteins that can...
Rab Cascades01:25

Rab Cascades

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.
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: