Freezing Cell Pellets for Large-Scale Immunoprecipitation

The advance, large-scale preparation of 10⁸-10⁹ adherent or suspension cells before the performance of immunoprecipitation can be advantageous given the time commitment required. The freezing of cells before lysis can preserve protein-protein interactions and posttranslational modifications that may otherwise become denatured and/or degraded upon initiation of cell lysis. This method can also be applied to the preparation of adherent or suspension cells on a smaller scale and is especially useful when multiple time points are being investigated over the course of several days or weeks. Cells are grown under optimal culturing conditions to promote a high degree of viability before being rinsed twice in phosphate-buffered saline (PBS), scraped into a polypropylene tube, and pelleted by centrifugation. The resulting cell pellet is frozen and can be stored for several months at -80°C.