ENU-induced A to T transversion at base pair 66,400,255 (v38) on chromosome 5, or base pair 218,563 in the GenBank genomic region NC_000071 encoding Apbb2. The mutation corresponds to residue 1,433 in the mRNA sequence NM_001201415 within exon 6 of 16 total exons. The mutation results in a threonine (T) to serine (S) substitution at position 288 (T288S) in the APBB2 protein.