A gene trap vector including a beta-galactosidase and neo was inserted into intron 2. The allele is predicted to result in a null or a severely hypomorphic mutation, with the in-frame fusion of the first 114 amino acids to the transmembrane Beta-gal and neo construct. A transcript with the expected size for the fused RNA was detected in Northern blot of mutant brain lysates, and Western blot showed a peptide of the size of the predicted fusion product instead of the two peptides detected in wild-type brain lysates.