Rxrg^tm1Ysa

A cassette containing lacZ and neo genes was inserted into the isoform-specific exon 2. By targeting exon 2, transcription of the isoform most prominent in brain tissue is ablated, while the isoform which is produced from a transcript in which exon 1b splices to exon 3, and is most abundant in skeletal muscle, is unaffected. RT-PCR analysis confirmed that the transcript encoding the targeted isoform was absent and that the level of transcript encoding the isoform that is most prominent in skeletal muscle was normal. X-gal staining showed that beta-galactosidase is expressed via the endogenous promoter. (J:77613)