CDK2AP1/DOC-1 is a bona fide subunit of the Mi-2/NuRD complex

The Mi-2/NuRD (NUcleosome Remodeling and histone Deacetylase) chromatin remodeling complex is a large heterogeneous multiprotein complex associated with transcriptional repression. Here we apply a SILAC based quantitative proteomics approach to show that all known Mi-2/NuRD complex subunits co-purify with Cyclin Dependent Kinase 2 Associated Protein1 (CDK2AP1), also known as Deleted in Oral Cancer 1 (DOC-1). DOC-1 displays in vitro binding affinity for methylated DNA as part of the meCpG binding MBD2/NuRD complex. In luciferase reporter assays, DOC-1 is a potent repressor of transcription. Finally, immunofluorescence experiments reveal co-localization between MBD2 and DOC-1 in mouse NIH-3T3 nuclei. Collectively, these results indicate that DOC-1 is a bona fide subunit of the Mi-2/NuRD chromatin remodeling complex.