Understanding the rate of the ratchet is important, for example, to estimate the number of beneficial mutations required to halt the ratchet and prevent the mutational meltdown of a population (Lynch et al. 1993; Goyal et al. 2012; Pfaffelhuber et al. 2012) (for an in-depth and up-to-date discussion of the importance of deleterious mutations we refer the reader to Charlesworth 2012).
The relative importance of mutator pathways in tumorigenesis increases as the number, C, of oncogenic mutations required to generate a malignant phenotype increases, as judged by α50% values.
We report a method based on analysis of multiple sequence alignments, embodied in our program Janus, for predicting mutations required to interconvert structurally related but functionally distinct enzymes.
Cells are thought to become cancerous over many years as they collect, one by one, the mutations required to override the many genetic restraints on a cell's growth.
B The two mutations required to make the GR insensitive to aldosterone (L111Q and S106P) both make the hormone insensitive to cortisol if they occur by themselves, and it is unlikely that both arose simultaneously.
This strategy grows out of the emerging view of cancer not as a state but as a process — a decades-long trek to accumulate the six to ten genetic mutations required to turn normal cells into an invasive tumor.
Phylogenetic trees of the A/H5N1 HA are shown in Fig. 1, color-coded by the number of nucleotide mutations required to obtain the five Herfst et al. set (column 1) and four Imai et al. set (column 2) of substitutions in HA.
The ALS-inducing variants were introduced into the pseudoWT C6A/C111S background to enhance reversibility of folding [46], and the monomeric proteins also contained the F50E/G51E mutations required to prevent dimerization [47], [48].
The greater enhancement of number of cancers compared to the enhancement of the number of polyps can be anticipated based on the greater number of oncogenic mutations required to produce the former.
As the PTB binding curve for the mBS2+3 mutant was the same as the triple mutant, it was concluded that the minimum combination of mutations required to reduce PTB binding were in BS2 and 3. Clearly, although mutation of BS2 and 3 reduced PTB binding, some residual binding activity remained (Fig 4).
