Related Experiment Video

Updated: Apr 17, 2026

Fully Processed Recombinant KRAS4b: Isolating and Characterizing the Farnesylated and Methylated Protein
07:08

Fully Processed Recombinant KRAS4b: Isolating and Characterizing the Farnesylated and Methylated Protein

Published on: January 16, 2020

6.2K

Mechanisms of membrane binding of small GTPase K-Ras4B farnesylated hypervariable region

Hyunbum Jang1, Sherwin J Abraham2, Tanmay S Chavan3

  • 1From the Basic Science Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research and Cancer and Inflammation Program, NCI-Frederick, National Institutes of Health, Frederick, Maryland 21702.

The Journal of Biological Chemistry
|February 26, 2015
PubMed

Insights

K-Ras4B membrane association is key to cancer. Its farnesyl group inserts into lipid microdomains, with rigid domains restricting penetration, impacting oncogenic function and signaling regulation.

Area of Science:

  • Molecular Biology
  • Biophysics
  • Cell Biology

Background:

  • K-Ras4B, a small GTPase, regulates cell growth, differentiation, and survival.
  • K-Ras4B mutations are common in cancer, with its plasma membrane association critical for oncogenic function.
  • The precise structural mechanisms of K-Ras4B membrane association remain incompletely understood.

Purpose of the Study:

  • To elucidate the structural mechanisms governing K-Ras4B's association with plasma membrane domains.
  • To investigate the role of K-Ras4B's C-terminal hypervariable region (HVR) modifications in membrane targeting and function.
  • To understand how membrane microdomain properties influence K-Ras4B localization and activity.

Main Methods:

  • Confocal microscopy to visualize K-Ras4B distribution.
  • Surface plasmon resonance (SPR) to quantify membrane binding kinetics.
  • Molecular dynamics (MD) simulations to model K-Ras4B-membrane interactions at the atomic level.

Main Results:

  • K-Ras4B exhibits differential distribution in rigid and loosely packed membrane domains.
  • Membrane fluidity dictates K-Ras4B membrane binding, with farnesyl group insertion favoring disordered lipid microdomains.
  • Rigid microdomains restrict farnesyl penetration, potentially promoting K-Ras4B oligomerization and influencing its orientation and phospholipid interactions.
  • Phosphorylation of Ser-181 inhibits spontaneous farnesyl membrane insertion.

Conclusions:

  • K-Ras4B HVR modifications, including farnesylation and positive charge, are crucial for targeting specific plasma membrane microdomains.
  • Membrane microdomain characteristics significantly regulate K-Ras4B localization and membrane orientation.
  • These findings suggest a novel regulatory role for the HVR in modulating Ras signaling pathways beyond simple membrane anchoring.
Keywords:
CooperativityHVRMembrane MicrodomainsPhospholipidPhosphorylationPost-translational Modification (PTM)Protein Isoprenylation

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

10.5K
Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells10:27

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

Published on: March 9, 2012

11.3K

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:
5.8K
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...
5.5K
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.
3.8K
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,...
10.3K
GTPases and their Regulation02:14

GTPases and their Regulation

3.3K
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...
7.6K