Pilot T J, Fox J L
Proc Natl Acad Sci U S A. 1984 Nov;81(22):6983-7. doi: 10.1073/pnas.81.22.6983.
Synthetic oligonucleotide probes were used to identify a cloned DNA fragment from the cyanobacterium Agmenellum quadruplicatum that contains the genes for the alpha and beta subunits of C-phycocyanin. The coding region for the alpha-subunit gene begins 108 base pairs downstream from the 3' end of the beta-subunit structural gene. The sequences of the coding regions for both genes have been determined as well as 379 base pairs of 5' flanking region, 204 base pairs of 3' flanking region, and the 108 base pairs between the two genes. The site of transcriptional initiation is located approximately equal to 325 base pairs upstream from the beta-subunit gene, and an open reading frame 114 base pairs long is found within this region. The significance of this additional open reading frame is not yet known. The derived amino acid sequences for both C-phycocyanin subunits were compared with other known C-phycocyanin sequences for homology. Homologies between the A. quadruplicatum alpha subunit and alpha subunits from other species were approximately equal to 70%, as were homologies between the A. quadruplicatum beta subunit and other beta subunits. Homologies between the various alpha and beta subunits were 21%-27%. Codon usage for both the C-phycocyanin alpha- and beta-subunit genes shows asymmetries for many amino acids that correspond closely to those seen in highly expressed Escherichia coli genes.
合成寡核苷酸探针被用于从蓝细菌四倍体节球藻中鉴定一个克隆的DNA片段，该片段包含C-藻蓝蛋白α和β亚基的基因。α亚基基因的编码区从β亚基结构基因3'端下游108个碱基对处开始。已确定了两个基因编码区的序列以及5'侧翼区的379个碱基对、3'侧翼区的204个碱基对和两个基因之间的108个碱基对。转录起始位点位于β亚基基因上游约325个碱基对处，并且在该区域内发现了一个114个碱基对长的开放阅读框。这个额外开放阅读框的意义尚不清楚。将两个C-藻蓝蛋白亚基推导的氨基酸序列与其他已知的C-藻蓝蛋白序列进行同源性比较。四倍体节球藻α亚基与其他物种α亚基之间的同源性约为70%，四倍体节球藻β亚基与其他β亚基之间的同源性也是如此。不同α和β亚基之间的同源性为21%-27%。C-藻蓝蛋白α和β亚基基因的密码子使用情况显示，许多氨基酸存在不对称性，这与在高表达的大肠杆菌基因中观察到的情况非常相似。
