Homology maps of the Drosophila alpha-tubulin gene family: one of the four genes is different.

We describe the intron-exon structure of and the homology among the four alpha-tubulin genes of Drosophila melanogaster. Three of the genes share a highly conserved 1.3 kb sequence which corresponds to most of the RNA complementary portion of the genes. The fourth gene is different. Its 5' half has weak homology and its 3' half has moderate homology to the other three genes. The homology maps were first determined by electron microscopy of heteroduplexes between pairs of genes. Higher resolution maps were then obtained by gel analysis of heteroduplexes that had been digested with S1 nuclease.