Related Experiment Video
Updated: Jan 31, 2026
Author Spotlight: Exploring Plasma Membrane Repair Mechanisms with Innovative Thermoplasmonic Puncturing
Published on: January 19, 2024
Quantitative biophysical analysis defines key components modulating recruitment of the GTPase KRAS to the plasma
Bindu Lakshman1, Simon Messing1, Eva M Schmid2
1From the NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, Maryland 21702.
Abstract:
The gene encoding the GTPase KRAS is frequently mutated in pancreatic, lung, and colorectal cancers. The KRAS fraction in the plasma membrane (PM) correlates with activation of the mitogen-activated protein kinase (MAPK) pathway and subsequent cellular proliferation. Understanding KRAS's interaction with the PM is challenging given the complexity of the cellular environment. To gain insight into key components necessary for KRAS signal transduction at the PM, we used synthetic membranes such as liposomes and giant unilamellar vesicles. Using surface plasmon resonance (SPR) spectroscopy, we demonstrated that KRAS and Raf-1 proto-oncogene Ser/Thr kinase (RAF1) domains interact with these membranes primarily through electrostatic interactions with negatively charged lipids reinforced by additional interactions involving phosphatidyl ethanolamine and cholesterol. We found that the RAF1 region spanning RBD through CRD (RBDCRD) interacts with the membrane significantly more strongly than the isolated RBD or CRD domains and synergizes KRAS partitioning to the membrane. We also found that calmodulin and phosphodiesterase 6 delta (PDE6δ), but not galectin3 previously proposed to directly interact with KRAS, passively sequester KRAS and prevent it from partitioning into the PM. RAF1 RBDCRD interacted with membranes preferentially at nonraft lipid domains. Moreover, a C-terminal O-methylation was crucial for KRAS membrane localization. These results contribute to a better understanding of how the KRAS-membrane interaction is tuned by multiple factors whose identification could inform drug discovery efforts to disrupt this critical interaction in diseases such as cancer.
Insights
Understanding KRAS protein interactions with cell membranes is key for cancer drug discovery. This study reveals how KRAS binds to membranes and how other proteins influence this critical process.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- The KRAS gene is frequently mutated in various cancers, including pancreatic, lung, and colorectal.
- KRAS localization to the plasma membrane (PM) is essential for activating the MAPK pathway, driving cellular proliferation.
- The complex cellular environment makes studying KRAS-PM interactions challenging.
Purpose of the Study:
- To elucidate the key molecular components and mechanisms governing KRAS signal transduction at the plasma membrane.
- To investigate the role of specific protein domains and lipids in KRAS membrane association.
- To identify factors that regulate KRAS partitioning to the PM for potential therapeutic targeting.
Main Methods:
- Utilized synthetic membranes (liposomes, giant unilamellar vesicles) to model the cellular environment.
- Employed surface plasmon resonance (SPR) spectroscopy to quantify KRAS and RAF1 domain interactions with membranes.
- Investigated the influence of various proteins (calmodulin, PDE6δ, galectin3) and lipid compositions on KRAS membrane localization.
Main Results:
- KRAS and RAF1 domains interact with membranes via electrostatic forces with negatively charged lipids, enhanced by phosphatidyl ethanolamine and cholesterol.
- The RAF1 RBDCRD region strongly promotes KRAS membrane partitioning, more so than isolated domains.
- Calmodulin and PDE6δ sequester KRAS, inhibiting its PM localization, while RAF1 RBDCRD favors non-raft lipid domains.
- C-terminal O-methylation of KRAS is critical for its membrane association.
Conclusions:
- KRAS-membrane interactions are complex, involving electrostatic forces, specific protein domains like RAF1 RBDCRD, and lipid composition.
- Proteins like calmodulin and PDE6δ act as negative regulators of KRAS PM localization.
- Understanding these regulatory factors, including C-terminal O-methylation, provides insights for developing drugs to disrupt KRAS signaling in cancer.
More Related Videos
Related Concept Videos
02:14GTPases and their Regulation
Large G-proteins,...
02:14GTPases and their Regulation
01:22Enlargement of the Plasma Membrane
01:27Plasma Membrane in Bacteria and Archaea
01:26Fusion of Secretory Vesicles with the Plasma Membrane
In 1993, Jim Rothman proposed that the antiparallel pairing of vesicular and transmembrane SNAREs, or...
01:12Quantitative Analysis
In quantitative analysis, two key measurements are made: the sample quantity and a property proportional to the amount of the analyte (the substance being analyzed). This forms the basis of the...