Defining Proximity Proteome of Histone Modifications by Antibody-mediated Protein A-APEX2 Labeling

Xinran Li, Jiaqi Zhou, Wenjuan Zhao, Qing Wen, Weijie Wang, Huipai Peng, Yuan Gao, Kelly J. Bouchonville, Steven M. Offer, Kuiming Chan, Zhiquan Wang, Nan Li, Haiyun Gan

Research output: Contribution to journalArticlepeer-review


Proximity labeling catalyzed by promiscuous enzymes, such as APEX2, has emerged as a powerful approach to characterize multiprotein complexes and protein–protein interactions. However, current methods depend on the expression of exogenous fusion proteins and cannot be applied to identify proteins surrounding post-translationally modified proteins. To address this limitation, we developed a new method to label proximal proteins of interest by antibody-mediated protein A-ascorbate peroxidase 2 (pA-APEX2) labeling (AMAPEX). In this method, a modified protein is bound in situ by a specific antibody, which then tethers a pA-APEX2 fusion protein. Activation of APEX2 labels the nearby proteins with biotin; the biotinylated proteins are then purified using streptavidin beads and identified by mass spectrometry. We demonstrated the utility of this approach by profiling the proximal proteins of histone modifications including H3K27me3, H3K9me3, H3K4me3, H4K5ac, and H4K12ac, as well as verifying the co-localization of these identified proteins with bait proteins by published ChIP-seq analysis and nucleosome immunoprecipitation. Overall, AMAPEX is an efficient method to identify proteins that are proximal to modified histones.

Original languageEnglish (US)
Pages (from-to)87-100
Number of pages14
JournalGenomics, Proteomics and Bioinformatics
Issue number1
StatePublished - Feb 2022


  • Modified histone
  • Post-translationally
  • Proximity labeling

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Genetics
  • Computational Mathematics


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