Department of Biology, Dalhousie University, Halifax, NS, B3H 4J1 Canada.
Biochem Cell Biol. 2009 Dec;87(6):989-97. doi: 10.1139/o09-050.
Tubulin is a heterodimeric protein composed of alpha- and beta-tubulin. In most organisms, they are encoded by multiple gene families whose members are subject to differential regulation. The objective of the work described herein was to better understand tubulin gene expression in the extremophile Artemia franciscana To this end tubulin cDNAs were cloned and sequenced. alphaAT2, an alpha-tubulin cDNA, differed by one nucleotide from alphaAT1, a previously cloned Artemia cDNA. This change, possibly generated by allelic variation, caused an M313V substitution in alpha-tubulin. The amino acid sequence of beta-tubulin encoded by betaAT1, one of only a very limited number of cloned crustacean beta-tubulin cDNA sequences yet available, and the first from Artemia, was similar to other beta-tubulins. However, betaAT1 possessed four degenerate TATA boxes in the 5' untranslated region, although authentic TATA and CCAAT boxes occurred in the 3' non-coding sequence. Analyses by quantitative PCR demonstrated that the amount of tubulin mRNA declined relative to total mRNA in progressive life history stages of Artemia and also that the organism contained more alphaAT2- than betaAT1-tubulin mRNA at all developmental phases examined.
微管蛋白是由α-和β-微管蛋白组成的异二聚体蛋白。在大多数生物体中，它们由多个基因家族编码，其成员受到差异调控。本文描述的工作的目的是更好地了解极端生物卤虫的微管蛋白基因表达。为此，克隆并测序了微管蛋白 cDNA。αAT2，一个α-微管蛋白 cDNA，与之前克隆的卤虫 cDNAαAT1 仅在一个核苷酸上不同。这种变化可能是由等位基因变异引起的，导致α-微管蛋白中的 M313V 取代。βAT1 编码的β-微管蛋白的氨基酸序列，是仅有的少数已克隆甲壳类动物β-微管蛋白 cDNA 序列之一，也是来自卤虫的第一个β-微管蛋白序列，与其他β-微管蛋白相似。然而，βAT1 在 5'非翻译区有四个退化的 TATA 盒，尽管在 3'非编码序列中存在真实的 TATA 和 CCAAT 盒。通过定量 PCR 分析表明，随着卤虫生活史阶段的逐渐进行，微管蛋白 mRNA 的数量相对于总 mRNA 减少，并且在所有研究的发育阶段，该生物中αAT2-比βAT1-微管蛋白 mRNA 多。
