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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:
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...
Structure and Function of Platelets01:18

Structure and Function of Platelets

The cell fragments known as platelets are disc-shaped, with an average diameter of about 3 μm and a thickness of roughly 1 μm. They play a crucial role in the body's vascular clotting system, which also involves plasma proteins, blood cells, and blood vessel tissues.
Platelets are continually replenished, circulating in the bloodstream for 9-12 days before being removed by phagocytes, primarily in the spleen. A microliter of circulating blood contains between 150,000 and 450,000 platelets, with...
Directionality of Nuclear Transport01:42

Directionality of Nuclear Transport

Ras-related nuclear protein or Ran is a small G protein that cycles between its GTP and GDP bound states. Ran specific regulators, a Ran GTPase Activating Protein or RanGAP present in the cytosol and a Ran guanine nucleotide exchange factor or RanGEF present inside the nucleus regulate GTP/GDP exchange. A high concentration of GTP inside the cells, in addition to this asymmetric distribution of  Ran-specific regulators, leads to a higher RanGTP concentration inside the nucleus. This...
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...

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Related Experiment Video

Updated: May 29, 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

Characterization of the Rac guanine nucleotide exchange factor P-Rex1 in platelets.

Joseph E Aslan1, Alex M Spencer, Cassandra P Loren

  • 1Department of Biomedical Engineering, Oregon Health & Science University, 3303 SW Bond Avenue, Mail Code CH13B, Portland, OR 97239 USA. aslanj@ohsu.edu.

Journal of Molecular Signaling
|September 3, 2011
PubMed
Summary

Platelet activation relies on Rac1, but the Rac guanine nucleotide exchange factor P-Rex1 is not essential for this process. P-Rex1

More Related Videos

Affinity Precipitation of Active Rho-GEFs Using a GST-tagged Mutant Rho Protein (GST-RhoA(G17A)) from Epithelial Cell Lysates
11:28

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

Turbidimetry on Human Washed Platelets: The Effect of the Pannexin1-inhibitor Brilliant Blue FCF on Collagen-induced Aggregation
09:13

Turbidimetry on Human Washed Platelets: The Effect of the Pannexin1-inhibitor Brilliant Blue FCF on Collagen-induced Aggregation

Published on: April 6, 2017

Related Experiment Videos

Last Updated: May 29, 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

Affinity Precipitation of Active Rho-GEFs Using a GST-tagged Mutant Rho Protein (GST-RhoA(G17A)) from Epithelial Cell Lysates
11:28

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

Turbidimetry on Human Washed Platelets: The Effect of the Pannexin1-inhibitor Brilliant Blue FCF on Collagen-induced Aggregation
09:13

Turbidimetry on Human Washed Platelets: The Effect of the Pannexin1-inhibitor Brilliant Blue FCF on Collagen-induced Aggregation

Published on: April 6, 2017

Area of Science:

  • Hematology
  • Cell Biology
  • Molecular Biology

Background:

  • Platelets are crucial for hemostasis and thrombosis.
  • Platelet shape change and aggregation depend on actin cytoskeletal remodeling.
  • The Rho GTPase Rac1 orchestrates these cytoskeletal changes.

Purpose of the Study:

  • To identify proteins that regulate Rac1 in platelets.
  • To investigate the role of P-Rex1 in platelet function.

Main Methods:

  • Protein capture and mass spectrometry to identify Rac1 interactors.
  • Western blotting to confirm protein expression and association.
  • Analysis of platelets from P-Rex1 knockout mice.

Main Results:

  • P-Rex1 was identified as a Rac1-interacting protein in platelets.
  • P-Rex1 is expressed in platelets and associates with Rac1.
  • P-Rex1-deficient platelets showed normal responses to agonists and activating surfaces.

Conclusions:

  • P-Rex1 is not required for Rac1-mediated platelet activation.
  • P-Rex1's guanine nucleotide exchange factor activity may be specific to other cellular processes, like GPCR signaling in immune and tumor cells.