α-tubulin genes of drosophila

Abstract

Four Drosophila α-tubulin genes have been isolated on recombinant DNA molecules. The identity of two of these genes (Tα1 and Tα2) was established by isolating complementary mRNAs and then examining the in vitro translation products of the mRNAs. The one- and two-dimensional gel patterns and the peptide maps of the in vitro products were indistinguishable from those of embryonic α-tubulin. In turn, the embryonic tubulin was identified by determining its amino-terminal sequence. We identified two other cloned α-tubulin genes (Tα3 and Tα4) by their complementarity to Tα1 and Tα2. Maps of restriction endonuclease sites indicate that the four genes are different. DNA hybridization studies demonstrated, however, that three of them have extensive sequence homology with each other and slight homology with the fourth, Tα4. Hybridization to genomic DNA fragments indicated that the four cloned genes account for all of the different α-tubulin genes of Drosophila melanogaster. Three of them are present only once in the haploid genome; the other, Tα1, is present in either one or two copies. Each of the four genes hybridizes in situ to a different site on the third chromosome (67C4-6, 84B3-C8, 84D5-8 and 85E6-15).