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Title
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Structure and sequence of the Drosophila melanogaster calmodulin gene.
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Authors
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V.L.Smith,
K.E.Doyle,
J.F.Maune,
R.P.Munjaal,
K.Beckingham.
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Ref.
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J Mol Biol, 1987,
196,
471-485.
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PubMed id
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Abstract
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A series of phage clones overlapping the single calmodulin gene locus of
Drosophila melanogaster has been isolated and the exons of the gene positioned
and sequenced within these clones. A calmodulin cDNA clone of the electric eel
was used to identify these clones and to position the two major protein-coding
exons of the gene. cDNA clones for D. melanogaster calmodulin were then
isolated, characterized and used to identify the remaining exons. The gene
consists of four exons separated by three introns of 3400 to 4300 bases in
length. Exon 1 consists of the 5' untranslated region and the initiator ATG;
exon 2 encodes amino acid residues 1 to 58.3; exon 3 encodes residues 58.3 to
139.3; and exon 4 encodes residues 139.3 to 148 and the 3' untranslated region.
From the sequence of the 3' untranslated region and the lengths of the cDNA
clones, two or three polyadenylation sites are indicated. Sequences potentially
involved in the control of transcription of the gene and splicing of the mRNA
product have been identified. Comparison of the intron-exon structures of the D.
melanogaster calmodulin gene, the chick calmodulin gene, and other genes of the
troponin C superfamily reinforces previous hypotheses that these genes arose
from a common progenitor and permits identification of four introns that were
probably present in the progenitor gene structure. The D. melanogaster
calmodulin gene contains three of these introns, and the chick gene contains all
four. These gene comparisons also indicate that the region of these genes
encoding Ca2+-binding loop 3 is highly variable in structure. The chick and D.
melanogaster calmodulin genes differ in this region, the chick gene containing a
fifth intron here that is absent from the D. melanogaster gene.
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