Genomic sequence spanning part of exon 1 through exon 3 was replaced with (from 5' to 3'): a loxP site, lacZ gene, frt-flanked neo cassette, loxP site, and polyadenylation site. The absence of full-length protein expression was confirmed by western blot analysis on brain extracts. Small amounts of a truncated peptide is detected. (J:158427)