Dnase2b^tm1Osa

Exons 3 and 4 were replaced with a neomycin selection cassette inserted by homologous recombination. Included in the deleted region were codons for 2 conserved histidine residues that are putative enzymatic active sites. Truncated transcript lacking the targeted sequence, and consequently containing a frameshift mutation, was detected in mutant mice by both Northern and RT-PCR analyses. Absence of DNAse activity under acidic conditions indicated that stable and functional protein was not produced by the mutant transcript. (J:85215)