Indeed, all of the tumors from patients who carried this particular T-to-A mutation also had additional mutations that inactivate the APC gene.
It turns out that all of the bird species share genetic mutations that inactivate genes involved in the formation of both tooth enamel and the portion of the tooth called dentin.
Since point mutations that inactivate the transcription termination function of GGT restore downstream promoter activity, the ability to block read-through transcription is the only property of GGT that is required for inhibition [21], [22].
Additionally, mutations that inactivate the key signal components, including receptors and Smads, are frequently observed within the tumor.
In contrast, if removing inhibitors will increase fitness, point mutations that inactivate the inhibitors will be selected, as we observed.
Forward mutations that inactivate the HSV-tk protein are scored after transfection of E. coli and selective plating.
This limitation can be bypassed by natural selection of mutations that inactivate the expression of self-glycans (Bishop and Gagneux, 2007).
In agreement with this notion, point mutations that inactivate the catalytic activity of Caf1 complement the phenotype of Caf1Δ cells and do not affect deadenylation [ 40].
The importance of Btk in the activation process is demonstrated most clearly by mutations that inactivate the kinase function of the molecule.
There is, however, a very important difference between mutations that inactivate genes, and those that result in new or different functions: in diploid individuals, having just one functional copy of a gene is very often sufficient, and most mutations that inactivate genes will thus be recessive, and thus have no detectable phenotype in heterozygous individuals.
Previous studies in budding yeast showed that production of uncapped transcripts caused by mutations that inactivate the capping machinery can lead to co-transcriptional recruitment of Xrn2 and premature transcription termination [ 55].
