Igh-7^tm1Lam

A point mutation was targeted to the third codon of exon 6 to introduce a stop codon and a frameshift mutation to the portion of the gene that encodes the cytoplasmic tail. LoxP sites were also inserted upstream of exon 5 and downstream of the mutated exon 6. A neomycin/tk selection cassette followed by a third loxP site was inserted further downstream. Transient expression of cre recombinase removed the selection cassette while leaving the mutated exon 6 in place. Correct targeting and recombination were confirmed by Southern blotting. This allele was predicted to encode an IgE heavy chain with a cytoplasmic tail only 3 amino acids long (KVK) that was identical to the cytoplasmic domain of mIgM and mIgD. (J:146733)