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Updated: Mar 13, 2026

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

Published on: January 16, 2020

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Structural basis of recognition of farnesylated and methylated KRAS4b by PDEδ

Srisathiyanarayanan Dharmaiah1, Lakshman Bindu1, Timothy H Tran1

  • 1NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21701.

Proceedings of the National Academy of Sciences of the United States of America
|November 3, 2016
PubMed

Insights

Structural studies reveal how Phosphodiesterase-δ (PDEδ) binds to farnesylated-methylated KRAS4b, crucial for KRAS signaling. This interaction, driven by KRAS4b

Area of Science:

  • Molecular Biology
  • Structural Biology
  • Biochemistry

Background:

  • KRAS4b post-translational modifications, farnesylation and carboxymethylation, are critical for plasma membrane localization and KRAS-mediated signaling.
  • Phosphodiesterase-δ (PDEδ) is a key protein involved in targeting prenylated KRAS4b to cellular membranes.

Purpose of the Study:

  • To elucidate the structural basis of the interaction between human farnesylated-methylated KRAS4b and PDEδ.
  • To identify structural features that dictate PDEδ binding specificity to prenylated proteins.

Main Methods:

  • X-ray crystallography to solve structures of KRAS4b-PDEδ complexes in two crystal forms.
  • Sequence analysis to identify conserved binding motifs.
  • Comparative structural analysis of PDEδ complexes with various prenylated proteins.

Main Results:

  • The structures reveal that KRAS4b binds PDEδ via its C-terminal amino acids and the farnesylated/methylated C185 residue, which fits into PDEδ's hydrophobic pocket.
  • A 5-amino acid motif (Lys-Ser-Lys-Thr-Lys) in KRAS4b is identified as potentially mediating PDEδ binding to both farnesylated and geranylgeranylated forms.
  • A larger protein-protein interaction interface in the KRAS4b-PDEδ complex compared to other PDEδ complexes was observed.

Conclusions:

  • The KRAS4b-PDEδ complex structure provides detailed insights into the molecular interactions governing KRAS4b membrane targeting.
  • The identified binding motif and interaction interface offer potential targets for developing specific inhibitors of KRAS-PDEδ interaction.
  • Understanding these interactions can help explain differential binding of PDEδ to various prenylated proteins, including why some, like KRAS4a, do not bind.
Keywords:
KRAS4bKRAS–PDEδ complexphosphodiesterase-δprenylationprotein–protein interaction

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