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Updated: Jun 30, 2025
Fully Processed Recombinant KRAS4b: Isolating and Characterizing the Farnesylated and Methylated Protein
Published on: January 16, 2020
A Top-Down Proteomic Assay to Evaluate KRAS4B-Compound Engagement
Robert A D'Ippolito1, Dana Rabara1, Maria Abreu Blanco1
1NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702, United States.
Abstract:
Development of new targeted inhibitors for oncogenic KRAS mutants may benefit from insight into how a given mutation influences the accessibility of protein residues and how compounds interact with mutant or wild-type KRAS proteins. Targeted proteomic analysis, a key validation step in the KRAS inhibitor development process, typically involves both intact mass- and peptide-based methods to confirm compound localization or quantify binding. However, these methods may not always provide a clear picture of the compound binding affinity for KRAS, how specific the compound is to the target KRAS residue, and how experimental conditions may impact these factors. To address this, we have developed a novel top-down proteomic assay to evaluate in vitro KRAS4B-compound engagement while assessing relative quantitation in parallel. We present two applications to demonstrate the capabilities of our assay: maleimide-biotin labeling of a KRAS4BG12D cysteine mutant panel and treatment of three KRAS4B proteins (WT, G12C, and G13C) with small molecule compounds. Our results show the time- or concentration-dependence of KRAS4B-compound engagement in context of the intact protein molecule while directly mapping the compound binding site.
Insights
A new top-down proteomic assay evaluates KRAS4B-compound engagement and binding site mapping. This method offers improved insights into targeted inhibitor development for KRAS mutations.
Area of Science:
- Biochemistry
- Proteomics
- Oncology
Background:
- Targeted inhibitors for oncogenic KRAS mutants are crucial in cancer therapy.
- Current proteomic methods for validating KRAS inhibitors may lack precision in assessing binding affinity and specificity.
- Understanding KRAS-compound interactions at the protein residue level is essential for drug development.
Purpose of the Study:
- To develop a novel top-down proteomic assay for evaluating in vitro KRAS4B-compound engagement.
- To assess relative quantitation of KRAS4B-compound interactions in parallel.
- To demonstrate the assay's capability in mapping compound binding sites on intact KRAS4B proteins.
Main Methods:
- Development of a novel top-down proteomic assay.
- Application 1: Maleimide-biotin labeling of a KRAS4B G12D cysteine mutant panel.
- Application 2: Treatment of wild-type, KRAS4B G12C, and KRAS4B G13C proteins with small molecule compounds.
Main Results:
- The assay successfully evaluated in vitro KRAS4B-compound engagement.
- Demonstrated time- and concentration-dependence of KRAS4B-compound interactions.
- Directly mapped compound binding sites on the intact KRAS4B protein molecule.
Conclusions:
- The novel top-down proteomic assay provides enhanced insights into KRAS4B-compound interactions.
- This assay can accurately assess binding affinity, specificity, and binding site localization.
- The developed method is valuable for validating targeted inhibitors in KRAS-driven cancer research.
