Jan 13, 2026
  • Yongjia Duan1
  • 1Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
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Protocol CitationYongjia Duan 2026. Microscopy-based bead protein–protein interaction assay. protocols.io https://dx.doi.org/10.17504/protocols.io.4r3l21jojg1y/v1
License: This is an open access  protocol  distributed under the terms of the  Creative Commons Attribution License,  which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Protocol status: Working
We use this protocol and it's working
Created: November 12, 2025
Last Modified: January 13, 2026
Protocol  Integer ID: 232243
Keywords: ASAPCRN, bead protein, protein interaction, assay microscopy, based gsh, protein, microscopy, assay, based bead protein
Funders Acknowledgements:
Aligning Science Across Parkinson’s (ASAP) initiative
Grant ID: ASAP-000350
Abstract
Microscopy-based GSH bead protein-protein interaction assay
Wash pre-blocked glutathione sepharose beads (GE Healthcare) with the reaction buffer (25 mM HEPES at pH 7.5, 200 mM NaCl, 2 mM MgCl2 and 1 mM TCEP) three times.
Add 0.5 μM purified GST tagged protein, and incubate atRoom temperature for 00:03:00

3m
Add 500 nM purified fluorescent protein in total 70 μl
Incubate at Room temperature for 00:30:00 , samples were mixed with additional 100 μL reaction buffer.

30m
Transferred to the observation chamber for imaging.
Acquire images on a Nikon A1 confocal microscope with a Nikon Plan APO VC 20x/0.75 NA UV Microscope Objective.