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Rab鸟苷三磷酸酶是细胞膜转运机制的关键调节分子,与原虫的分泌功能密切相关。本研究旨在克隆和分析阴道毛滴虫Rab6鸟苷三磷酸酶同源基因,以便进一步探讨其功能。作者从阴道毛滴虫cDNA表达文库中分离出2个Rab6鸟苷三磷酸酶同源基因的cDNA克隆,其中1个cDNA序列长658对碱基,读码框含597对碱基,推测蛋白质序列具198个氨基酸。序列分析表明该氨基酸序列与Rab6a蛋白亚家族的同源性最高。另一cDNA序列长764对碱基,读码框含657对碱基,推测蛋白质序列具218个氨基酸。序列比对分析显示该氨基酸序列与Rab6b蛋白有较高的同源性。2个氨基酸序列都拥有Rab鸟苷三磷酸酶家族的所有保守结构域、特异性RabF结构域和典型的异戊烯化结构域。进化树分析提示毛滴虫的这2个基因系Rab6家族的同源基因,在进化上更接近原虫和单细胞的酵母Rab6亚家族。序列分析还显示这2个基因都无内含子,其基因组DNA序列与其cDNA序列完全一致。
Rab guanosine triphosphatase is a key regulator of cell membrane transport mechanisms, and the secretion of protozoa are closely related. This study aimed to clone and analyze Trichomonas vaginalis Rab6 guanosine triphosphatase homologous genes in order to further explore its function. The authors isolated two cDNA clones of Rab6 guanosine triphosphatase homologous genes from the Trichomonas vaginalis cDNA expression library. One cDNA sequence was 658 bp in length and the reading frame contained 597 bp. The predicted protein sequence With 198 amino acids. Sequence analysis showed that this amino acid sequence has the highest homology with the Rab6a protein subfamily. The other cDNA was 764 bp in length and contained 657 nucleotides in frame, suggesting that the protein sequence has 218 amino acids. Sequence alignment analysis showed that this amino acid sequence has high homology with Rab6b protein. Both amino acid sequences possess all the conserved domains of the Rab guanosine triphosphatase family, the specific RabF domain, and the typical prenylation domain. Phylogenetic tree analysis suggested that these two genes of Trichomonas strain are homologs of the Rab6 family, which are evidently closer to the protozoan and unicellular yeast Rab6 subfamily. Sequence analysis also showed that these two genes have no introns and their genomic DNA sequences are exactly the same as their cDNA sequences.