Molecular basis of spontaneous mutation at the aprt locus of hamster cells.
Mutations occurring spontaneously at the hamster aprt locus were examined at the base-pair level by amplifying target sequences using the polymerase chain reaction and then directly sequencing the double-stranded products. In a collection of 89 sequenced genes, all types of mutations were found, with transitions (mostly G.C to A.T) constituting the largest class (35%), transversions accounting for 27%, and small deletions/duplications for 25%. Simple base substitutions were distributed throughout the aprt structural gene with few sites having recurring mutations and G.C base-pairs being the predominant substitution target. Small deletions, on the other hand, were not distributed so evenly, being concentrated in a region of aprt rich in short direct and inverted repeat sequences. The base substitutions were predominantly missense, while about 10% produced nonsense codons. Splice junctions, and start and stop codons were also significant targets for mutation. No alterations were detected in three aprt-deficient strains after sequencing all exons and substantial upstream and downstream regions.
Phear
G
G
Imperial Cancer Research Fund, Clare Hall Laboratories, Hertfordshire, U.K.
Armstrong
W
W
Meuth
M
M
D000228:Adenine Phosphoribosyltransferase / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D002872:Chromosome Deletion; D006224:Cricetinae; D004252:DNA Mutational Analysis; D015723:Gene Library; D005796:Genes; D005810:Multigene Family; D010430:Pentosyltransferases / Q000235:genetics*; D016133:Polymerase Chain Reaction
D010430:Pentosyltransferases; D000228:Adenine Phosphoribosyltransferase