[View Larger Version of this Image]

Figure S1. Gene targeting strategy to produce AID^S38A and AID^T140A mice. AID S38 or T140 was mutated to alanine using this gene-targeting strategy. As indicated, the long arm (LA) of the targeting vector was 5 kb long, with the 3′ within the intron between AID exons 2 and 3. The short arm (SA) was a 3.3-kb fragment extending with the 3′ into the intron between exons 3 and 4. A LoxP-flanked neomycin resistance gene was used for positive selection (ACN), and a diphtheria toxin gene (not depicted) was used for negative selection.