Wang D, Shatkin A J
Nucleic Acids Res. 1984 Mar 12;12(5):2303-15. doi: 10.1093/nar/12.5.2303.
Guanylyltransferase that catalyzes mRNA capping by the reaction, ppNpN + GTP----GpppNpN was purified from S. cerevisiae. The enzyme forms a nucleotidyl intermediate by phosphoamide linkage of GMP. Two guanylylated polypeptides of MR approximately 52,000 and 46,000 were obtained, the latter apparently by proteolysis of the larger component. Both forms transferred the covalently bound GMP to ppApG, yielding GpppApG. Dinucleoside tri- and tetraphosphates of the type Gp3N and Gp4N were also produced by using ribonucleoside 5'-di and triphosphates as acceptors. The purified yeast guanylyltransferase contained little or no RNA 5'-triphosphatase or methyltransferase.
通过ppNpN + GTP→GpppNpN反应催化mRNA加帽的鸟苷酸转移酶从酿酒酵母中纯化得到。该酶通过GMP的磷酰胺键形成核苷酸中间体。得到了两条分子量约为52,000和46,000的鸟苷酸化多肽，后者显然是较大成分经蛋白水解产生的。两种形式都将共价结合的GMP转移到ppApG上，生成GpppApG。使用核糖核苷5'-二磷酸和三磷酸作为受体时，还产生了Gp3N和Gp4N类型的二核苷三磷酸和四磷酸。纯化的酵母鸟苷酸转移酶几乎不含有或不含有RNA 5'-三磷酸酶或甲基转移酶。
