Guerini D, Montell C, Klee C B
Laboratory of Biochemistry, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892.
J Biol Chem. 1992 Nov 5;267(31):22542-9.
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.
利用高度保守的人类cDNA探针，从黑腹果蝇基因组文库中分离出了包含钙调神经磷酸酶（一种Ca2+/钙调蛋白刺激的蛋白磷酸酶）两个亚基完整编码序列的基因组克隆。三个克隆编码了一个19.3 kDa的蛋白，其序列与人类钙调神经磷酸酶B（钙调神经磷酸酶的Ca(2+)结合调节亚基）的序列有88%的同一性。果蝇和人类钙调神经磷酸酶B基因的编码序列有69%的同一性。果蝇钙调神经磷酸酶B是位于X染色体4F位置的一个无内含子单基因的产物。编码钙调神经磷酸酶A（钙调神经磷酸酶的催化亚基）高度保守区域的果蝇基因组克隆，被用于将钙调神经磷酸酶A基因定位在果蝇第二条染色体的21 EF位置，并从果蝇胚胎cDNA文库中分离出钙调神经磷酸酶A cDNA克隆。通过比较基因组和cDNA序列确定了钙调神经磷酸酶A基因的结构。发现12个外显子，分布在总共6.6千碱基上，编码一个64.6 kDa的蛋白，与人类钙调神经磷酸酶Aα或β有73%的同一性。在核苷酸水平上，果蝇钙调神经磷酸酶A cDNA与人类钙调神经磷酸酶Aα和β cDNA分别有67%和65%的同一性。人类和果蝇钙调神经磷酸酶A之间的主要差异局限于氨基和羧基末端，包括果蝇分子羧基末端三分之一处的两段重复序列。蛋白磷酸酶-1和-2A以及钙调神经磷酸酶假定催化中心的特征基序几乎完全保守。所有哺乳动物钙调神经磷酸酶A特有的钙调蛋白结合和自身抑制结构域也保守。钙调神经磷酸酶A基因的一个显著特征是内含子/外显子连接处位于功能结构域的边界，并且从果蝇到人类内含子/外显子连接处明显保守。
