Thra^tm2Jas

Exons 5 through 7 were replaced with a cassette comprised of lacZ and neo. The targeting vector was designed to abolish transcription of the four known isoforms produced from this locus. The deleted region encoded the DNA-binding domain found in the two larger isoforms and the internal promoter in intron 7 that drives the transcription of the two truncated isoforms. Northern blot and RT-PCR analyses of intestinal RNA showed the absence of all four transcripts in homozygous mutant mice. RNA protection assays revealed the occasional presence of the truncated transcripts resulting from sporadic readthrough of the stop codons contained within the inserted cassette. (J:70007)