Molecular analysis of the intergenic region of the duplicated amy genes of drosophila melanogaster and drosophila teissieri

Abstract

The intergenic regions between the duplicated amylase coding regions (Amy) of D. melanogaster and D. teissieri were sequenced. Their lengths in D. melanogaster and D. teissieri were 4,536 bp and 4,621 bp, respectively. Since homology between the upstream regions of the two duplicated genes was found up to 450 bp from the initiation codon of the Amy genes, the ancestral Amy coding region duplicated together with at least 450 bp of the 5'-flanking region as one unit. Comparison of the regions between the two species revealed that the level of divergence was very heterogeneous. Although the mean level of the nucleotide difference in this region was 0.107, no nucleotide substitution was found in four subregions whose sizes were more than 100 bp. Since the probability of these four subregions being completely conserved between D. melanogaster and D. teissieri was very low, these subregions were considered to have relatively important roles in evolution. Large insertions and deletions were not observed in this region but small ones were observed all over the region except for an about 1-kb subregion. This 1-kb region corresponded to an open reading frame encoding a protein which had some sequence identity with the proteins of the serine protease inhibitor superfamily (serpin). Since we could find a transcript of this gene and the synonymous substitution rate was higher than the replacement substitution rate, we suggest that this gene encodes an active serpin in Drosophila.

Serpin Structure, Mechanism, and Function

“…Only one has been well characterized as a cloned protein . Another has been identified as a gene encoding an active serpin, and the presence of one has been inferred from its ability to form a higher molecular weight covalent complex with the serine proteinase Easter . A study aimed at identifying proteins produced by the male accessory gland and secreted into seminal fluid identified 12 such proteins, one of which (Acp76A) was a serpin (orphan) …”

Molecular Characterization of STAT5A- and STAT5B-Encoding Genes Reveals Extended Intragenic Sequence Homogeneity in Cattle and Mouse and Different Degrees of Divergent Evolution of Various Domains

“…Thus, it was found that the expressed, functional Supt4h2 gene was created by reintegration of a processed mRNA transcript of the Supt4h gene on a different chromosome, under the control of a new, previously unrelated promoter. Likewise, the extremely high degree of intraspecific sequence conservation of an intergenic region (>1000 bp) between two copies of duplicated amylase genes within the Drosophila species complex is due to another functional gene which is encoded by the conserved area (Okuyama et al 1997).…”