Gene trapping in ES cells is a random insertional mutagenesis approach to functional genomics. The gene trap vector is designed to generate sequence, expression and functional information for each clone. The basic gene trap vector contains a splice acceptor site immediately upstream of a promoterless reporter gene and a selectable marker, shown below.
The gene trap vector is introduced into ES cells by electroporation or retroviral infection and clones containing gene trap insertions are selected by antibiotic resistance. Antibiotic resistant clones are then picked into 96-well master plates, which are later replicated to generate frozen stocks for long-term storage of clones, cell lysates for RNA and DNA isolation followed by PCR-based gene identification techniques.