Complete turnover of poly(A) on maternal mRNA of sea urchin embryos
Complete turnover of poly(A) on maternal mRNA of sea urchin embryos
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Poly(A) 对海胆胚胎母体 mRNA 的完全转换
DOI：
10.1016/0092-8674(77)90050-2
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发表时间：
1977
期刊：
影响因子：
64.5
通讯作者：
T. Humphreys
中科院分区：
文献类型：
--
作者：
G. Dolecki;R. Duncan;T. Humphreys
对受精海胆卵的前体池和poly（A）中放射性腺苷掺入量的测量表明，孵育2小时后，掺入poly（A）中的腺苷量接近胚胎的总poly（A）含量。观察到无论是在受精时多聚腺苷酸含量增加三倍时开始孵育，还是在受精后2.5小时多聚腺苷酸水平不变时开始孵育，因此表明多聚腺苷酸持续和完全翻转。转换似乎发生在多聚核糖体mRNA上，因为在孵育10或120分钟后，75%的3 H-腺苷掺入多聚腺苷酸（A）在多聚核糖体上。受精前后Poly（A）长度没有显著差异，表明poly（A）含量的增加反映了poly（A）序列添加到先前不含poly（A）序列或仅含短poly（A）序列的mRNA分子上。新的和先前存在的多聚腺苷酸束都必须翻转以产生我们所观察到的结合。通过腺苷的碱性释放测量的放射性聚腺苷酸束开始为短序列，并逐渐延长其长度，直到它们达到与聚腺苷酸序列已完全放射性的想法一致的大小。这种标记模式表明poly（A）可能通过缩短和延长机制从3 '末端翻转。
Measurement of the incorporation of radioactive adenosine into precursor pools and into poly (A) of fertilized sea urchin eggs showed that the amount of adenosine incoporated into poly (A) after a 2 hr incubation approximated the total poly (A) content of the embryos. This was observed whether the incubation was begun at fertilization when the poly (A) content is tripling or at 2.5 hr after fertilization when the poly (A) levels are not changing, and thus indicates that poly (A) turns over continually and completely. The turnover appears to take place on polysomal mRNA, since after either 10 or 120 min of incubation, 75% of the 3H-adenosine incorporated into poly (A) is on polysomes. Poly (A) lengths before and after fertilization are not significantly different, indicating that the increase in poly (A) content reflects the addition of poly (A) sequences onto mRNA molecules which previously contained no poly (A) sequences or only short poly (A) sequences. Both the new as well as the preexisting poly (A) tracts must turn over to produce the incorporation we observe. The radioactive poly (A) tracts measured by alkaline release of adenosine begin as short sequences and gradually extend their lengths until they have reached a size consistent with the idea that the poly (A) sequences have become fully radioactive. This labeling pattern shows that the poly (A) is turning over from the 3’end terminal probably by a shortening and lengthening mechanism.