Gene Tagging with the CRISPR-Cas9 System to Facilitate Macromolecular Complex Purification

The need to generate modified cell lines that express tagged proteins of interest has become increasingly important. Here, we describe a detailed protocol for facile CRISPR/Cas9-mediated gene tagging and isolation of modified cells. In this protocol, we combine two previously published strategies that promote CRISPR/Cas9-mediated gene tagging: using chemically modified single-stranded oligonucleotides as donor templates and a co-selection strategy targeting the ATP1A1 gene at the same time as the gene of interest. Altogether, the protocol proposed here is both easier and saves time compared to other approaches for generating cells that express tagged proteins of interest, which is crucial to purify native complex from human cells.