Functional replacement of Drosophila Btk29A with human Btk in male genital development and survival

Drosophila type 2 Btk29A reveals the highest homology to Btk among mammalian Tec kinases. In Btk29AficP mutant males, the apodeme holding the penis split into two pieces. Human Btk rescued this phenotype in 39% of Btk29AficP males, while the Drosophila transgenes did so in 90–100% of mutants. The Btk29AficP mutation reduced adult longevity to 11% that of wild-type. This effect was counteracted by Drosophila type 2, yielding 76% of the wild-type lifespan. Human Btk extended the lifespan of Btk29AficP mutants only to 20% that of wild-type. Thus human Btk can partially replace Drosophila Btk29A+ in male genital development and survival.