Tseng B Y, Goulian M
J Biol Chem. 1980 Mar 10;255(5):2062-6.
Nearest neighbor frequencies in initiator RNA (iRNA) of a human lymphocyte cell line have been measured in isolated nuclei under conditions where ribonucleotides have been omitted from the incubation. Deoxynucleotides are incorporated in iRNA to a limited extent for the omitted cognate ribonucleotide. In addition, upon omission of a ribonucleotide, changes in the nearest neighbor frequencies also occur indicating base substitution of another ribonucleotide. The base substitutions that have been observed are the incorporation of rA for rG or rU. Substitution for rA has not been observed. When rC is omitted, a change in all nearest neighbor frequencies occurs, suggesting possibly an unusual role for rC. The substitutions demonstrate the unique features of iRNA synthesis and point out possible alterations in iRNA that may occur in vivo when nucleotide pools are altered.
在人淋巴细胞系起始RNA（iRNA）中，已在孵育过程中省略核糖核苷酸的条件下，对分离细胞核中的最近邻频率进行了测量。对于省略的同源核糖核苷酸，脱氧核苷酸在有限程度上掺入iRNA。此外，当省略一种核糖核苷酸时，最近邻频率也会发生变化，表明另一种核糖核苷酸发生了碱基取代。观察到的碱基取代是用rA取代rG或rU。未观察到用其他碱基取代rA的情况。当省略rC时，所有最近邻频率都会发生变化，这可能表明rC具有特殊作用。这些取代证明了iRNA合成的独特特征，并指出了在体内核苷酸库发生变化时iRNA可能发生的改变。
