DNA methyltransferase I (DNMT1) plays a key role in establishing and maintaining patterns of DNA methylation. Dysregulation of DNA methylation is associated with different kinds of cancer. The goal of this study was to identify DNMT1 interacting proteins with a view to understanding how DNMT1 is itself regulated.

We used a novel affinity purification-mass spectrometry (AP-MS) work flow that makes use of endogenously tagged cell-lines (Zhang et al, 2008) to identify DNMT1-interacting proteins. Epitope (FLAG) tagged DNMT1 protein was expressed in colorectal cancer (RKO) cells and DNMT1 protein complexes recovered using anti-FLAG antibody. Gel-free mass spectrometry proteomics was used to identify DNMT1-interacting proteins.

We identified ubiquitin-specific peptidase 7 (USP7) as a DNMT1 interacting protein and subsequently showed that USP7 regulates DNMT1 stability through de-ubiquitination (thus protecting DNMT1 from proteasomal degradation) (Du et al, 2010).

Tasks & Questions



Raw Data

MS/MS spectra from AP-MS experiment (a filtered subset of the spectra are provided)

MS/MS spectra from Control experiment

Search Results

Identified proteins from AP-MS experiment

Identified proteins from Control experiment

Taxonomy: Homo sapiens


Du et al. DNMT1 Stability Is Regulated by Proteins Coordinating Deubiquitination and Acetylation-Driven Ubiquitination. Science Signaling, 2010 (paper|PubMed).

Zhang et al. Epitope tagging of endogenous proteins for genome-wide ChIP-chip studies. Nat Methods, 2008 (PubMed)