Kalderon D, Rubin G M
Howard Hughes Medical Institute, Department of Biochemistry, University of California, Berkeley 94720.
Genes Dev. 1988 Dec;2(12A):1539-56. doi: 10.1101/gad.2.12a.1539.
We have used mammalian probes to clone genes encoding the catalytic (C) and type I regulatory (RI) components of the cAMP-dependent protein kinase in Drosophila. Both Drosophila gene products are very similar in amino acid sequence (RI, 71%; C, 82%) to their respective mammalian counterparts, implying homologous activity. A single Drosophila type I regulatory subunit gene is the source of at least three distinct transcripts originating from different promoters and spliced to a common body that would encode a full-length analog and two amino-terminally truncated variants of the mammalian RI protein. The RI locus also includes two intronic genes of unknown function. A single highly conserved catalytic subunit gene (DC0) was found that codes for a single polypeptide. It was used to isolate 11 further more distantly related apparent protein kinase genes. Two of these genes (DC1 and DC2) are sufficiently similar to DC0 in sequence (45% and 49% amino acid identity, respectively) that they could conceivably encode products of overlapping function. Two further genes are very similar in sequence to bovine cGMP-dependent protein kinase. The remaining putative gene products include amino acid sequence motifs characteristic of serine-threonine protein kinases but cannot, from the available data, be defined as homologous to specific protein kinases of other organisms.
我们利用哺乳动物的探针克隆了果蝇中编码环磷酸腺苷（cAMP）依赖性蛋白激酶催化（C）亚基和I型调节（RI）亚基的基因。果蝇的这两种基因产物与其相应的哺乳动物对应物在氨基酸序列上非常相似（RI为71%，C为82%），这意味着它们具有同源活性。果蝇的单个I型调节亚基基因是至少三种不同转录本的来源，这些转录本起源于不同的启动子，并剪接到一个共同的主体上，该主体将编码哺乳动物RI蛋白的全长类似物和两种氨基末端截短的变体。RI基因座还包括两个功能未知的内含子基因。我们发现了一个高度保守的催化亚基基因（DC0），它编码一种单一的多肽。利用该基因又分离出另外11个亲缘关系更远的明显的蛋白激酶基因。其中两个基因（DC1和DC2）与DC0在序列上足够相似（氨基酸同一性分别为45%和49%），以至于它们可能编码具有重叠功能的产物。另外两个基因与牛的环磷酸鸟苷（cGMP）依赖性蛋白激酶在序列上非常相似。其余推定的基因产物包含丝氨酸 - 苏氨酸蛋白激酶特有的氨基酸序列基序，但根据现有数据，无法确定它们与其他生物体的特定蛋白激酶同源。
