A FLAGELLAR CALMODULIN GENE OF NAEGLERIA, COEXPRESSED DURING DIFFERENTIATION WITH FLAGELLAR TUBULIN GENES, SHARES DNA, RNA, AND ENCODED PROTEIN-SEQUENCE ELEMENTS
A FLAGELLAR CALMODULIN GENE OF NAEGLERIA, COEXPRESSED DURING DIFFERENTIATION WITH FLAGELLAR TUBULIN GENES, SHARES DNA, RNA, AND ENCODED PROTEIN-SEQUENCE ELEMENTS
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DOI：
10.1074/jbc.270.11.5839
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发表时间：
1995-03-17
影响因子：
4.8
通讯作者：
REMILLARD, SP
中科院分区：
文献类型：
--
作者：
FULTON, C;LAI, EY;REMILLARD, SP
格鲁氏耐格里阿米巴从变形虫到鞭毛虫分化过程中合成了两种钙调素;一个留在细胞体中，另一个定位在鞭毛中。鞭毛钙调素的单个、无内含子的表达基因已被克隆和测序，编码的蛋白质是典型的钙调素，具有四个推定的钙结合结构域，但它在保守的钙调蛋白残基4之前具有10个不同氨基酸的氨基末端延伸。编码鞭毛钙调蛋白和鞭毛细胞体钙调蛋白的转录本明显不同，鞭毛钙调蛋白基因的表达是分化特异性的;其mRNA与编码鞭毛α-和β-微管蛋白的mRNA同时出现然后消失，这些不相关的共表达基因共享三个激发序列元件：（i）在每个转录区域的上游发现一式两份或一式三份的回文DNA序列元件;（ii）在鞭毛钙调蛋白和α-微管蛋白的AUG起始密码子附近发现完美的12个核苷酸匹配;鞭毛钙调蛋白的氨基端延伸包含一个与鞭毛α-微管蛋白氨基端相似的5-氨基酸序列元件，这些共有的序列元件被认为在分化中起作用，可能在转录调节、mRNA稳定性和这些蛋白质在鞭毛上的定位中起作用。
Two calmodulins are synthesized during differentiation of Naegleria gruberi from amoebae to flagellates; one remains in the cell body and the other becomes localized in the flagella, The single, intronless, expressed gene for flagellar calmodulin has been cloned and sequenced, The encoded protein is a typical calmodulin with four putative calcium-binding domains, but it has an amino-terminal extension of 10 divergent amino acids preceding conserved calmodulin residue 4. The transcripts encoding flagellar calmodulin and flagellate cell body calmodulin are clearly divergent, Expression of the flagellar calmodulin gene is differentiation specific; its mRNA appears and then disappears concurrently with those encoding flagellar alpha- and beta-tubulin, Three provocative sequence elements are shared among these unrelated coexpressed genes: (i) a palindromic DNA sequence element is found in duplicate or triplicate upstream to each transcribed region; (ii) a perfect 12-nucleotide match is found near the AUG start codon of flagellar calmodulin and alpha-tubulin; and (iii) the novel amino-terminal extension of flagellar calmodulin contains a 5-amino-acid element similar to the amino terminus of flagellar alpha-tubulin, These shared sequence elements are proposed to have roles in differentiation, possibly in regulation of transcription, mRNA stability, and localization of these proteins to flagella.