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Updated: Jan 18, 2026

Analysis of Endocytic Uptake and Retrograde Transport to the Trans-Golgi Network Using Functionalized Nanobodies in Cultured Cells
Published on: February 21, 2019
Atypical GPCR Activation Resolved by Nanobody Engineering
Roman R Schlimgen1,2, Shawn E Jenjak1, Alexa De La Sancha1
1Department of Biochemistry, Medical College of Wisconsin, Milwaukee, USA.
Researchers discovered a new way G protein-coupled receptors (GPCRs) activate, focusing on extracellular pocket volume changes instead of traditional conformational shifts. This finding offers novel strategies for targeting difficult-to-treat receptors.
Area of Science:
- Biochemistry
- Structural Biology
- Pharmacology
Background:
- G protein-coupled receptors (GPCRs) are a major drug target class.
- Most therapeutics target only a small fraction of well-characterized GPCRs.
- The atypical chemokine receptor ACKR3 presents unique challenges due to its broad ligand recognition and high basal activity.
Purpose of the Study:
- To elucidate the unconventional activation mechanism of the ACKR3 receptor.
- To challenge established paradigms of GPCR activation.
- To identify new strategies for modulating GPCRs, including pharmacologically intractable ones.
Main Methods:
- Engineered nanobodies
- Cryo-electron microscopy (cryo-EM)
- Nuclear Magnetic Resonance (NMR) spectroscopy
- Structure-guided pharmacology
Main Results:
- ACKR3 activation is controlled by extracellular pocket volume, not conserved microswitch conformational changes.
- An expanded aromatic cluster in the intracellular transducer binding pocket stabilizes the active receptor state.
- This reveals an unconventional mechanism distinct from canonical GPCR activation models.
Conclusions:
- ACKR3 activation mechanism redefines GPCR modulation strategies.
- Findings provide new avenues for targeting previously intractable GPCRs.
- This research broadens the understanding of GPCR signaling and drug discovery potential.
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