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Updated: Jul 2, 2025

Comparing the Affinity of GTPase-binding Proteins using Competition Assays
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Comparing the Affinity of GTPase-binding Proteins using Competition Assays

Published on: October 8, 2015

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Adapting recombinant bacterial alkaline phosphatase for nucleotide exchange of small GTPases

Peter H Frank1, Min Hong1, Brianna Higgins1

  • 1NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, 21702, USA.

Protein Expression and Purification
|February 23, 2024
PubMed

Insights

Researchers developed an alternative to CIP-agarose for nucleotide exchange in RAS proteins. Bacterial alkaline phosphatase (BAP) bound to beads effectively replaces GDP with GTP analogs, aiding cancer research.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Cancer Research

Background:

  • Rat sarcoma virus proteins (RAS) are crucial regulators of cell growth, implicated in 20-30% of human cancers.
  • RAS proteins cycle between active (GTP-bound) and inactive (GDP-bound) states, necessitating nucleotide exchange for studying the active form.

Purpose of the Study:

  • To develop an alternative to commercially unavailable Calf intestine alkaline phosphatase bound to agarose beads (CIP-agarose).
  • To establish a reliable method for nucleotide exchange in RAS proteins using accessible laboratory materials.

Main Methods:

  • Generation of bacterial alkaline phosphatase (BAP) with an affinity tag.
  • Immobilization of BAP onto agarose beads.
  • Validation of the BAP-agarose conjugate in a nucleotide exchange protocol.

Main Results:

  • The developed BAP-agarose conjugate effectively facilitated complete nucleotide exchange in RAS proteins.
  • This method provides a viable alternative to the standard CIP-agarose protocol.
  • The protocol utilizes generally available laboratory equipment.

Conclusions:

  • Bacterial alkaline phosphatase (BAP) immobilized on agarose beads serves as an effective substitute for CIP-agarose.
  • This alternative method addresses supply chain issues and supports continued research on RAS proteins in cancer.
Keywords:
Bacterial alkaline phosphatase (BAP)GTPGppNHpRASnucleotide exchange

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