Pafah1b1^{Gt(IRESBetageo)1Hha}

The expression of a testis-specific transcript was abrogated by the integration a gene trap vector into the endogenous locus. The vector inserted into intron 2 and consisted of an engrailed 2 intron, IRES, and beta-geo. RT-PCR analysis showed the level of a testis-specific transcript, containing exon 2a, to be markedly diminished in homozygous mutant mice. While protein was detected in homozygous mutant brain tissue by Western blot analysis, it was absent in the testes of mutant mice. (J:86720)