The construct for Tg(Igh-6/Igh-V281)3Jwt has a germ line reversion encoding D at residue 49 (from G)and another encoding V (from E) at residue 56. The transgene encodes an IgMa constant region with a variable region nearly identical to that of the BALB/c IgG1 mouse anti-human insulin monoclonal antibody, mAb125, (from the American Type Culture Collection) but lacking the high affinity specificity for insulin.