Related Experiment Video

Updated: Aug 10, 2026

A Functional Assay for Gap Junctional Examination; Electroporation of Adherent Cells on Indium-Tin Oxide
11:02

A Functional Assay for Gap Junctional Examination; Electroporation of Adherent Cells on Indium-Tin Oxide

Published on: October 18, 2014

The cytoplasmic protein GAP is implicated as the target for regulation by the ras gene product

C Calés1, J F Hancock, C J Marshall

  • 1Chester Beatty Laboratories, Institute of Cancer Research, London, UK.

Nature
|April 7, 1988
PubMed

Insights

Mutations in ras genes create oncoproteins driving tumor growth. Researchers found that GAP protein interacts with p21ras at the effector site, suggesting it

Area of Science:

  • Molecular biology
  • Oncology
  • Signal transduction

Background:

  • Approximately 30% of human tumors harbor mutations in ras genes, producing p21ras oncoproteins.
  • p21ras oncoproteins are implicated in the transformed phenotype of tumors.
  • The exact biochemical function of ras proteins remains unclear, though they bind GTP/GDP and possess GTPase activity, suggesting a role in regulating cell proliferation via plasma membrane signaling pathways.

Purpose of the Study:

  • To investigate the biochemical mode of action of ras proteins.
  • To identify the biological target for regulation by p21ras.
  • To elucidate the interaction between ras proteins and GAP.

Main Methods:

  • Interaction studies between p21ras and GAP.
  • Analysis of GTPase activity modulation by GAP.
  • Mapping the interaction site of GAP on p21ras.

Main Results:

  • GAP dramatically increases the GTPase activity of normal p21ras.
  • GAP does not affect the GTPase activity of p21ras oncoproteins.
  • GAP interacts with p21ras at a site identified as the 'effector' site.

Conclusions:

  • GAP is strongly implicated as the biological target regulated by p21ras.
  • Understanding the p21ras-GAP interaction is crucial for comprehending tumor development.
  • This finding provides insights into ras-mediated signal transduction in cancer.

More Related Videos

Comparing the Affinity of GTPase-binding Proteins using Competition Assays10:37

Comparing the Affinity of GTPase-binding Proteins using Competition Assays

Published on: October 8, 2015

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

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...
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...
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...
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: