Soluble tubulin complexes in oocytes of the common leopard frog, Rana pipiens, contain γ-tubulin
Soluble tubulin complexes in oocytes of the common leopard frog, Rana pipiens, contain γ-tubulin
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DOI：
10.1002/mrd.1069
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发表时间：
2001-09-01
影响因子：
2.5
通讯作者：
Kim, H
中科院分区：
文献类型：
--
作者：
Lessman, CA;Kim, H
卵母细胞的豹蛙，蛙，含有可溶性微管蛋白，这是以前被证明主要存在于兆道尔顿（MDa）馏分，并未能很容易地组装在体外。为了进一步表征这些微管蛋白复合物，使用DEAE Sepharose层析，Sephacryl S-300尺寸排阻柱和特异性免疫沉淀。结果表明，存在α-，β-和γ-微管蛋白与其他几种蛋白质的可溶性部分蛙pipiens卵巢卵母细胞。这些蛙卵母细胞微管蛋白复合物似乎类似于最近报道的非洲爪蟾排卵卵中的γ-微管蛋白环复合物。这似乎是真的，因为大小（估计值，即类似于2 MDa）和蛋白质组分都相似。此外，α-和γ-微管蛋白抗体从蛙卵母细胞可溶性级分免疫沉淀相同的蛋白质条带。这些推定的蛙γ-微管蛋白环蛋白包括107、97、95、90和75 kDa的组分，其大小与在非洲爪蟾和其它物种中发现的相似。蛙似乎属于其中γ-微管蛋白复合物含有显著的α-和β-微管蛋白（即，非洲爪蟾和绵羊），而其他物种，如果蝇，曲霉，酵母，人类细胞和许多其他哺乳动物细胞测试缺乏其他微管蛋白成分。蛙卵母细胞γ-微管蛋白环复合物的大小和蛋白组分的异质性可能反映了微管蛋白复合物组装的不同状态。低等脊椎动物卵母细胞被假设为γ-微管蛋白环复合物组装的储存库和预分期点，γ-微管蛋白环复合物将成为母体对胚胎中心体的贡献。虽然之前已经描述了脊椎动物卵的γ-微管蛋白环复合物，但这是第一次报告生物化学表征脊椎动物卵巢卵母细胞中的可溶性γ-微管蛋白复合物。
Oocytes of the leopard frog, Rana pipiens, contain soluble tubulin which was previously shown to exist predominately in megadalton (MDa) fractions and that fails to readily assemble in vitro. In order to further characterize these tubulin complexes, DEAE Sepharose chromatography, Sephacryl S-300 size exclusion columns and specific immunoprecipitation were used. The results revealed the presence of alpha-, beta-, and gamma -tubulin associated with several other proteins in the soluble fraction of Rana pipiens ovarian oocytes. These Rana oocyte tubulin complexes appear to be analogous to those recently reported in Xenopus ovulated eggs as gamma -tubulin ring complexes. This seems true since both size (estimates, i.e. similar to 2MDa) and protein components are similar. Furthermore, both alpha- and gamma -tubulin antibodies immunoprecipitated identical protein bands from Rana oocyte soluble fraction. These putative Rana gamma -tubulin ring proteins include 107, 97, 95, 90 and 75 kDa components which are similar in size to those found in Xenopus and other species. Rana appears to belong to a select group in which gamma -tubulin complexes contain significant alpha- and beta -tubulin (i.e., Xenopus and sheep), while other species such as Drosophila, Aspergillus, Saccharomyces, human cells and many other mammalian cells tested lack the other tubulin components. The heterogeneity in both size and protein components of Rana oocyte gamma -tubulin ring complexes may reflect different states of tubulin complex assembly. The lower vertebrate oocyte is hypothesized to act as a repository and prestaging point for the assembly of gamma -tubulin ring complexes which will become the maternal contribution to the centrosomes of the embryo. While the gamma -tubulin ring complexes of vertebrate eggs have been described previously, this is the first report biochemically characterizing soluble gamma -tubulin complexes in vertebrate ovarian oocytes.