Prat A, Katinka M, Caron F, Meyer E
J Mol Biol. 1986 May 5;189(1):47-60. doi: 10.1016/0022-2836(86)90380-3.
The complete DNA sequence of the G surface protein of Paramecium primaurelia has been determined. It contains an open reading frame of 8145 nucleotides devoid of introns and coding for a protein of 329,000 Mr. Analysis of the deduced amino acid sequence reveals remarkable features such as important internal homologies and a periodic structure, which could be dictated in part by the rigid scaffolding of cysteine residues. The predicted secondary structure shows a quasi absence of alpha-helix and an abundance of beta-pleated sheets and random coils. The monotony of the amino acid sequence is in favour of a structural role for the protein. Interestingly, homologies with other proteins are limited to surface antigens of trypanosomes. Finally, our data are consistent with a genetic code for paramecium which differs from the "universal" code by the assignment of TAA and TAG codons to glutamine.
已确定了嗜热四膜虫G表面蛋白的完整DNA序列。它包含一个8145个核苷酸的开放阅读框，没有内含子，编码一个分子量为329,000的蛋白质。对推导的氨基酸序列的分析揭示了显著特征，如重要的内部同源性和周期性结构，这可能部分由半胱氨酸残基的刚性支架决定。预测的二级结构显示几乎没有α-螺旋，而富含β-折叠片和无规卷曲。氨基酸序列的单调性有利于该蛋白发挥结构作用。有趣的是，与其他蛋白的同源性仅限于锥虫的表面抗原。最后，我们的数据与四膜虫的遗传密码一致，该密码与“通用”密码不同，它将TAA和TAG密码子分配给谷氨酰胺。
