Faust M, Millward S, Duchastel A, Fromson D
Cell. 1976 Dec;9(4 Pt 1):597-604. doi: 10.1016/0092-8674(76)90042-8.
We have examined the poly(A)- and poly(A)+ polyribosomal (Ps) RNAs of developing sea urchin embryos to see whether they contain the capped structures previously observed in the poly(A)+ cytoplasmic RNA (mRNA) of a variety of eucaryotic organisms. We have found that both classes of Ps RNA contain 7-methylguanosine linked to the RNA by a 5'-5' triphosphate bridge. Capped structures derived from either class of Ps RNA appear to be of the type m7G5'ppp5'NmpNp, with only a single sugar-methylated nucleoside per cap, and we have estimated that both classes of Ps RNA are capped to the same extent. The 5' terminal 2'-0-methylated nucleosides have been identified and quantitated. The relative amounts are Am = 78%, Gm = 14%, Cm = 5%, Um = 3% for poly(A)- Ps RNA, and Am = 78%, Gm = 15%, Cm = 5%, Um = 2% for poly (A)+ Ps RNA. In addition, both classes of Ps RNA contain 2-4 internal residues of N6-methyladenylic acid per molecule.
我们检测了发育中的海胆胚胎的多聚腺苷酸（poly(A)）和多聚腺苷酸阳性（poly(A)+）多核糖体（Ps）RNA，以确定它们是否含有先前在多种真核生物的多聚腺苷酸阳性细胞质RNA（mRNA）中观察到的帽状结构。我们发现这两类Ps RNA都含有通过5'-5'三磷酸桥与RNA相连的7-甲基鸟苷。源自这两类Ps RNA的帽状结构似乎是m7G5'ppp5'NmpNp类型，每个帽只有一个糖基化的核苷，并且我们估计这两类Ps RNA的加帽程度相同。已鉴定并定量了5'末端2'-O-甲基化核苷。对于多聚腺苷酸阴性（poly(A)-）Ps RNA，相对含量为Am = 78%，Gm = 14%，Cm = 5%，Um = 3%；对于多聚腺苷酸阳性（poly(A)+）Ps RNA，相对含量为Am = 78%，Gm = 15%，Cm = 5%，Um = 2%。此外，这两类Ps RNA每分子都含有2 - 4个N6-甲基腺苷酸的内部残基。
