Freezing Cell Pellets for Large-Scale Immunoprecipitation

Abstract

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.