The alpha-amylase gene in Drosophila mdanogaster: nucleotide sequence, gene structure and expression motifs

We present the complete nucleotide sequence of a Drosophlla α amylaae gene and its flanking regions, as determined by cDNA and genoralc sequence analysis. This gene, unlike Its mammalian counterparts, contains no lntrons. Nevertheless the Insect and mammalian genes share extensive nucleotide similarity and the Insect protein contains the four amlno acid sequence blocks common to all α-amylases. In Drosophlla melanogaster, there are two closely-linked copies of the αamylase gene and they are divergently transcribed. In the 5′- regions of the two gene-copies we find high sequence divergence, yet the typical eukaryotlc gene expression motifs have been maintained. The 5′-terminus of the α-amylase mRNA, as determined by primer extension analysis, maps to a characteristic Drosophila sequence motif. Additional conserved elements upstream of both genes may also be involved in amylase gene expression which is known to be under complex controls that include glucose repression.