2 DISTINCT GENES ENCODE 2 MAJOR ISOELECTRIC FORMS OF INSECTICYANIN IN THE TOBACCO HORNWORM, MANDUCA-SEXTA
2 DISTINCT GENES ENCODE 2 MAJOR ISOELECTRIC FORMS OF INSECTICYANIN IN THE TOBACCO HORNWORM, MANDUCA-SEXTA
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DOI：
10.1111/j.1432-1033.1992.tb16805.x
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发表时间：
1992-04-15
期刊：
影响因子：
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通讯作者：
RIDDIFORD, LM
中科院分区：
文献类型：
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作者：
LI, WC;RIDDIFORD, LM
昆虫花青素是一种存在于烟草天蛾（Manducasexta）表皮和血淋巴中的蓝色色素。分离出两种不同的全长cDNA种类，并显示其编码昆虫花青素的两种主要等电形式，a形式（INS-a）和B形式（INS-B）。对pE 1-I1和pE 3-I2两个cDNA克隆的序列分析表明，它们都含有一个618 bp的开放阅读框架，预测了一个189个氨基酸的蛋白质和一个17个氨基酸的信号肽，推导的INS-a和INS-b蛋白质在13个氨基酸上存在差异，其中6个是保守的。在推导的INS-b序列和从血淋巴中分离的测序的INS-b蛋白之间也发现了三个氨基酸替换。5个基因组克隆的分离和鉴定表明，pE 1-I1和pE 3-I2来自两个不同的基因。INS-a和INS-b基因都有四个外显子，在相同的位置被三个内含子中断。这两个基因在编码区有93%的核苷酸相似性。此外，“TATA盒”和“CAAT盒”在这两个基因的推定启动子区中是完全保守的。引物延伸显示，INS-a和INS-b基因开始其转录在相对于其翻译起始密码子ATG的位置-52。我们认为这两个基因是基因复制的结果。
Insecticyanin is a blue pigment found in the epidermis and hemolymph of the tobacco hornworm, Manduca sexta. Two distinct full-length cDNA species were isolated and shown to encode the two major isoelectric forms of insecticyanin, the a form (INS-a) and b form (INS-b). Sequence analysis of the two cDNA clones, pE1-I1 and pE3-I2, reveals that both contain an 618-bp open reading frame which predicts an 189-amino-acid protein and an 17-amino-acid signal peptide.Comparison of the deduced INS-a and INS-b proteins show 13 amino acid differences, of which six are conserved. Three amino acid substitutions are also found between the deduced INS-b sequence and the sequenced INS-b protein isolated from the hemolymph. Isolation and characterization of five genomic clones revealed that pE1-I1 and pE3-I2 come from two different genes. Both INS-a and INS-b genes have four exons interrupted by three introns at the same positions. The two genes share 93% nucleotide similarity in the coding region. Moreover, the 'TATA box' and 'CAAT box' are completely conserved in the putative promoter regions of the two genes. Primer extension revealed that both INS-a and INS-b genes begin their transcription at position -52 relative to their translation initiation codon, ATG. We conclude that the two genes are the result of gene duplication.