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Updated: Oct 8, 2025
Glutamine Flux Imaging Using Genetically Encoded Sensors
Published on: July 31, 2014
Identification of Glutamine Synthetase as a Contryphan-Bt Binding Protein by His-Tag Pull-Down
Penggang Han1, Shangyi Liu1, Xiandong Dai1
1Beijing Institute of Pharmaceutical Chemistry, Beijing 102205, China.
Background & Objective:
Contryphan-Bt is a D-tryptophan-containing disulfide-constrained decapeptide recently isolated from the venom of Conus betulinus. The molecular targets of contryphans are controversial, and the identification of its interacting proteins may be of great importance.
Methods:
His-tag pull-down assays were performed to investigate intracellular binding proteins of contryphan-Bt from rat brain lysate. Bt-Acp-[His]6, a contryphan-Bt derivative containing hexahistidine tag, was synthesized and used as the bait. As a control, Acp-[His]6 was used to exclude nonspecific bindings.
Results:
Glutamine synthetase was identified as a potential contryphan-Bt binding protein by pull-- down assays and subsequent LC-MS/MS. The binding of contryphan-Bt to glutamine synthetase was confirmed and determined using microscale thermophoresis, with a Kd of 74.02 ± 2.8 μM. The binding did not affect glutamine synthetase activity, suggesting that the interaction site was distinct from the catalytic center.
Conclusion:
Glutamine synthetase was identified as a novel contryphan-Bt binding protein. This is the first report in which the conopeptide binds to an intracellular protein.
