期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1986
卷号：83
期号：3
页码：710-714
DOI：10.1073/pnas.83.3.710
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The glucocorticoid response element (GRE) of mouse mammary tumor virus (MMTV) was chemically synthesized as two complementary DNA strands bearing cohesive termini. During automated synthesis, random mutations were introduced into the DNA by "doping" each of the four nucleoside phosphoramidites (A, G, C, and T) with a low level of the other three. These preparations were annealed and cloned into an M13 phage vector to produce a library of GRE mutants. Mutations within the synthesized region were identified by sequencing phage isolates at random. All of the chemically distinct classes of transition and transversion mutations have been observed. Statistical considerations indicate that the library contains all of the possible 90 point substitution mutations within a 30-nucleotide mutagenic target. So far 88 of these substitutions have been isolated, 74 as single mutants. At least two of the three possible single mutants at each of the 30 positions have been identified.
