Rpl22^tm1.1Psam

A loxP site was inserted upstream of the final coding exon (exon 4) and a loxP site and a frt-flanked neomycin cassette were inserted downstream of the exon. In addition, a modified version of exon 4 was knocked-in downstream of the neo cassette. This duplicated exon 4 contained 3 sequence repeats encoding hemagglutinin eptiope (HA) just upstream of the endogenous stop codon. Founder mice were crossed with FlpeR deleter mice to remove the neomycin cassette leaving exon 4 floxed. In the absence of cre recombinase, the stop codon in the endogenous exon 4 prevents translation of the knocked-in exon and only wild-type protein is expressed. In the presence of cre recombinase, the endogenous exon 4 is removed and the modified exon 4 is instead transcribed leading to a ribosomal complex tagged with HA-epitope. (J:151962)