GEF1 is a ciliary Sec7 GEF of Tetrahymena thermophila.
GEF1 is a ciliary Sec7 GEF of Tetrahymena thermophila.
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GEF1 是嗜热四膜虫的纤毛 Sec7 GEF。
DOI：
10.1002/cm.20348
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发表时间：
2009
影响因子：
--
通讯作者：
Satir,Peter
中科院分区：
文献类型：
--
作者：
Bell,AaronJ;Guerra,Charles;Phung,Vincent;Nair,Saraswathy;Seetharam,Raviraja;Satir,Peter
纤毛鸟嘌呤核苷酸交换因子（GEFs）在鞭毛内运输（IFT）货物释放中可能激活G蛋白。一些类型的全球环境因子已经定位于纤毛或基底，并显示出在预防纤毛病方面的重要功能，但纤毛arl型Sec 7相关的全球环境因子尚未得到很好的表征。Nair等人（1999）鉴定出一种纤毛草履虫Sec7 GEF， PSec7。在四膜虫中，经PSec7抗体初步鉴定的Gef1p （GEF1）具有纤毛和核靶向序列，与PSec7一样定位于纤毛和大核。GEF1 RNA的上调发生在纤毛脱落和纤毛再生之后。与类似的Psec7结构域相对应，gef1结构域除了包含GBF/BIG规范结构域外，还包含iq样结构域和推测的PH结构域。基因组分析鉴定了另外两个四膜虫GBF/BIG Sec7家族gef (GEF2, GEF3)，它们不具有纤毛靶向序列。对GEF1和GEF2进行HA修饰以确定细胞定位。转化后产生适当截断的GEF1-HA的细胞定位于体细胞和口腔纤毛，但不定位于大核。发现纤毛稳定性和功能的细微缺陷。GEF2-HA定位于基体附近，但不定位于纤毛。这些结果表明GEF1是与PSec7同源的常驻四膜虫纤毛蛋白。
Ciliary guanine nucleotide exchange factors (GEFs) potentially activate G proteins in intraflagellar transport (IFT) cargo release. Several classes of GEFs have been localized to cilia or basal bodies and shown to be functionally important in the prevention of ciliopathies, but ciliary Arl-type Sec 7 related GEFs have not been well characterized. Nair et al. (1999) identified a Paramecium ciliary Sec7 GEF, PSec7. In Tetrahymena, Gef1p (GEF1), tentatively identified by PSec7 antibody, possesses ciliary and nuclear targeting sequences and like PSec7 localizes to cilia and macronuclei. Upregulation of GEF1 RNA followed deciliation and subsequent ciliary regrowth. Corresponding to similar Psec7 domains, GEF1domains contain IQ-like motifs and putative PH domains, in addition to GBF/BIG canonical motifs. Genomic analysis identified two additional Tetrahymena GBF/BIG Sec7 family GEFs (GEF2, GEF3), which do not possess ciliary targeting sequences. GEF1 and GEF2 were HA modified to determine cellular localization. Cells transformed to produce appropriately truncated GEF1-HA showed localization to somatic and oral cilia, but not to macronuclei. Subtle defects in ciliary stability and function were detected. GEF2-HA localized near basal bodies but not to cilia. These results indicate that GEF1 is the resident Tetrahymena ciliary protein orthologous to PSec7.