The incorporation of an engineered point mutation in exon 13 created a glycine to alanine substitution at codon 674 (G674A), within the conserved ATPase domain of the C-terminal. A floxed neo-PGK-hygro cassette that was included in the targeting vector was removed by cre-mediated recombination leaving a single loxP site and the G674A mutation. Western blot analysis of homozygous mutant MEFs indicated expression of the mutant protein at wild-type levels. (J:88092)