To identify transcription factors of PRMT6 which could recruit PRMT6 to target genes, we used affinity purification of avi-tagged PRMT6 in combination with stable isotope labeling of amino acids in cell culture (SILAC) based mass spectrometry. For this, K562 cells were transduced with a lentiviral co expression vector for the BirA-ligase and avi-PRMT6 with a 21 amino acid taq, which is biotinylated in the cells. Cells expressing the BirA-ligase only served as a control. Avi-PRMT6 cells were grown in heavy SILAC medium and control cells in light SILAC medium for seven passages. Nuclear extracts were prepared from 1x108 cells and subjected to avi-PRMT6 affinity purification using magnetic streptavidin beads. Subsequently, the proteins were eluted from the beads. The eluates from the avi-PRMT6 and the control were mixed in a one to one ratio. Subsequently, we performed quantitative mass spectrometry (MS)-based analysis of the PRMT6 interactome.