ISSN:
1572-9931
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Biologie
,
Medizin
Notizen:
Abstract Clone B is a CHO cell line that showns a moderate mutator phenotype as a consequence of a defect in mismatch recognition. To identify the classes of mutation that accumulate spontaneously in a functional gene, we isolated and sequenced 54 clone B spontaneous mutants at the adenine phosphoribosyltransferase gene. This spectrum was compared to 42 mutants collected in the parental cells. Rates of AT→TA transversions and frameshifts were strikingly increased in clone B (almost eight- and sixfold, respectively). Minor increases were also observed for GC→TA transversions and GC→AT transition rates. Frameshifts occurred in repeated sequences, and a large proportion were losses of 2 bases occurring in dinucleotide runs of a type similar to microsatellite sequences. AT→TA transversions clustered in regions of secondary structure and their formation might be explained by slippage-mediated mechanisms. These data indicate that an important function of mismatch recognition is in repair of extrahelical bases generated by misalignment during DNA replication.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF02257458
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