Molecular cloning and characterization of the genes encoding the two subunits of Drosophila melanogaster calcineurin.
Genomic clones containing the full coding sequences of the two subunits of the Ca2+/calmodulin-stimulated protein phosphatase, calcineurin, were isolated from a Drosophila melanogaster genomic library using highly conserved human cDNA probes. Three clones encoded a 19.3-kDa protein whose sequence is 88% identical to that of human calcineurin B, the Ca(2+)-binding regulatory subunit of calcineurin. The coding sequences of the Drosophila and human calcineurin B genes are 69% identical. Drosophila calcineurin B is the product of a single intron-less gene located at position 4F on the X chromosome. Drosophila genomic clones encoding a highly conserved region of calcineurin A, the catalytic subunit of calcineurin, were used to locate the calcineurin A gene at position 21 EF on the second chromosome of Drosophila and to isolate calcineurin A cDNA clones from a Drosophila embryonic cDNA library. The structure of the calcineurin A gene was determined by comparison of the genomic and cDNA sequences. Twelve exons, spread over a total of 6.6 kilobases, were found to encode a 64.6-kDa protein 73% identical to either human calcineurin A alpha or beta. At the nucleotide level Drosophila calcineurin A cDNA is 67 and 65% identical to human calcineurin A alpha and beta cDNAs, respectively. Major differences between human and Drosophila calcineurins A are restricted to the amino and carboxyl termini, including two stretches of repetitive sequences in the carboxyl-terminal third of the Drosophila molecule. Motifs characteristic of the putative catalytic centers of protein phosphatase-1 and -2A and calcineurin are almost perfectly conserved. The calmodulin-binding and auto-inhibitory domains, characteristic of all mammalian calcineurins A, are also conserved. A remarkable feature of the calcineurin A gene is the location of the intron/exon junctions at the boundaries of the functional domains and the apparent conservation of the intron/exon junctions from Drosophila to man.
Guerini
D
D
Laboratory of Biochemistry, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892.
Montell
C
C
Klee
C B
CB
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019703:Calcineurin; D002148:Calmodulin-Binding Proteins / Q000235:genetics*; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004331:Drosophila melanogaster / Q000235:genetics*; D005091:Exons; D017344:Genes, Insect; D008969:Molecular Sequence Data; D010749:Phosphoprotein Phosphatases / Q000235:genetics*; D054645:Protein Phosphatase 1; D012326:RNA Splicing; D051381:Rats; D015183:Restriction Mapping; D016415:Sequence Alignment
D002148:Calmodulin-Binding Proteins; D019703:Calcineurin; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1