Ank1^M1Btlr

ENU-mutagenesis induced a T to C transition at position 24,145,986 bp on chromosome 8 corresponding to base pair 122,756 of the genomic DNA sequence of Ank1 (NC_000074). The mutation is within intron 13,791 nucleotides from exon 13 and 209 nucleotides from exon 14 (of 44 total exons). In contrast to the single 400 base pair band detected in the wild-type sample, three major cDNA fragments were detected: one corresponded to the size of wild-type Ank1 transcript, two additional fragments were observed at a higher molecular weight. The long splicing isoform contained a cryptic exon of 317 base pair as a result of the use of a preexisting 3' splice site that is 108 base pair upstream from the mutation. The short splicing isoform incorporated two cryptic exons as a result of the use of the aforementioned 3' splice site as well as two preexisting 5' and 3' splice sites downstream of the mutation. Both mutant transcripts introduced an in-frame stop codon that would result in truncation of the protein eight amino acids after residue 501; full-length aberrant mRNA was not detected, indicating nonsense-mediated decay of the mutant transcript occurred. Western blot anlaysis confirmed the reduction in protein expression in red blood cell ghost membranes. (J:203831)