Ribonucleoside uptake and phosphorylation during fertilization and early development of the sea-urchin, Strongylocentrotus purpuratus.
Ribonucleoside uptake and phosphorylation during fertilization and early development of the sea-urchin, Strongylocentrotus purpuratus.
复制标题
海胆 Strongylocentrotus purpuratus 受精和早期发育过程中核糖核苷的摄取和磷酸化。
DOI：
10.1111/j.1432-1033.1987.tb11198.x
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发表时间：
1987
期刊：
影响因子：
--
通讯作者：
Nishioka,D
中科院分区：
文献类型：
--
作者：
Killian,CE;Nishioka,D
在紫红色圆孔海胆（strongylocentrrotus purpuratus）的卵中，通常存在于RNA中的四种核糖核苷的摄取在受精后不久增加近50倍。尿苷、腺苷和胞苷在转运到受精卵后立即被磷酸化（约95%）为单磷酸、二磷酸和三磷酸。虽然鸟苷的运输程度与其他三种核糖核苷相同，但运输后磷酸化的鸟苷不到12%。对未受精卵匀浆进行的卵核苷和核苷酸激酶分析表明，在受精前，卵中存在尿苷、腺苷和胞苷激酶以及尿苷酸、腺苷酸、胞苷酸和鸟苷酸激酶。底物竞争测量表明腺苷磷酸化是由一种单特异性酶催化的，而尿苷和胞苷磷酸化是由一种共同的激酶催化的。未受精卵匀浆中未检测到鸟苷激酶活性。在受精后3 - 5小时，运输的鸟苷进入胚胎后磷酸化开始增加。在受精后7小时，超过95%进入胚胎的鸟苷被磷酸化成单磷酸、二磷酸和三磷酸。80%以上被磷酸化为三磷酸鸟苷。鸟苷磷酸化增加的时间与胚胎中酸溶性GTP库的减少相关，这表明鸟苷激酶活性的增加是对GTP需求增加的反应。鉴于GTP在许多细胞过程中的重要性，这些结果表明，在海胆发育早期，鸟苷激酶激活在GTP库维持和细胞代谢中起着至关重要的作用。
Uptake of the four ribonucleosides normally present in RNA increases nearly 50‐fold shortly after fertilization in eggs of the sea‐urchin,Strongylocentrotus purpuratus. Uridine, adenosine and cytidine are phosphorylated (>95%) to their mono‐, di‐ and triphosphates immediately after transport into the fertilized egg. Although guanosine is transported to an extent equal to the other three ribonucleosides, less than 12% of it is phosphorylated after transport.In vitronucleoside and nucleotide kinase assays of unfertilized egg homogenates indicate that the uridine, adenosine and cytidine kinases as well as the uridylate, adenylate, cytidylate and guanylate kinases are present in the egg prior to fertilization. Substrate competition measurements indicate that adenosine phosphorylation is catalyzed by a monospecific enzyme, while uridine and cytidine phosphorylations are catalyzed by a common kinase. Guanosine kinase activity was not detectable in unfertilized egg homogenates. Between 3 h and 5 h after fertilization the phosphorylation of transported guanosine begins to increase as it enters the embryo. By 7 h after fertilization, more than 95% of the guanosine entering the embryo is phosphorylated to the mono‐, di‐and triphosphates. More than 80% is phosphorylated to guanosine triphosphate. The timing of increased guanosine phosphorylation correlates with a decrease in the acid‐soluble GTP pools in the embryo, suggesting that increased guanosine kinase activity is a response to increased GTP demand. These results, in view of the importance of GTP in many cellular processes, imply a crucial role for guanosine kinase activation in GTP pool maintenance and cellular metabolism during early sea‐urchin development.