Falkenthal S, Lengyel J A
Biochemistry. 1980 Dec 9;19(25):5842-50. doi: 10.1021/bi00566a028.
We have characterized the copia RNA in the cytoplasm of cultured Drosophila cells. Copia RNA was detected and purified by hybridization to DNA of the plasmid cDm 1142, which contains the copia sequence. A large fraction (2.2%) of the total cytoplasmic poly(A)+ RNA was found to be copia RNA. Cytoplasmic copia RNA displays all the characteristics expected for a messenger RNA. It possesses a poly(A) tract identical in length with that of total poly(A)+ cytoplasmic RNA. It is associated with polysomes and can be released from this association by treatment with EDTA. When purified copia RNA is added to an mRNA-dependent rabbit reticulocyte lysate, three polypeptides of 51000, 33000, and 21000 daltons are seen. We have not determined if these are different polypeptides or if the two smaller polypeptides are fragments of the 51000-dalton polypeptide. The half-life of copia cytoplasmic RNA was determined in pulse--chase experiments to be 9.5 h; this is 1.6 times longer than the half-life of the intermediate decay class of total poly(A)+ cytoplasmic RNA. These properties provide strong evidence that copia RNA functions in vivo as a messenger RNA.
我们已对培养的果蝇细胞胞质中的考皮阿RNA进行了特性分析。通过与含有考皮阿序列的质粒cDm 1142的DNA杂交来检测和纯化考皮阿RNA。发现总胞质多聚腺苷酸（poly(A)）+ RNA中的很大一部分（2.2%）是考皮阿RNA。胞质考皮阿RNA具有信使RNA所预期的所有特性。它拥有一段长度与总胞质多聚腺苷酸（poly(A)）+ RNA相同的多聚腺苷酸尾。它与多核糖体相关联，并且可以通过用乙二胺四乙酸（EDTA）处理从这种关联中释放出来。当将纯化的考皮阿RNA添加到依赖信使RNA的兔网织红细胞裂解物中时，可以看到分子量分别为51000、33000和21000道尔顿的三种多肽。我们尚未确定这些是否是不同的多肽，或者两个较小的多肽是否是51000道尔顿多肽的片段。在脉冲追踪实验中确定考皮阿胞质RNA的半衰期为9.5小时；这比总胞质多聚腺苷酸（poly(A)）+ RNA的中等衰减类别的半衰期长1.6倍。这些特性提供了有力证据，证明考皮阿RNA在体内作为信使RNA发挥作用。
