At variance with the great majority of protein kinases that become active only in response to specific stimuli and whose implication in tumors is caused by genetic alterations conferring to them unscheduled activity, the highly pleiotropic Ser/Thr-specific protein kinase CK2 is constitutively active even under normal conditions and no gain-of-function CK2 mutants are known.
Several long-lived mutants are known which predominantly or exclusively respire via AOX.
In mouse, mutants are known for both the ligand, Eda-A1 (Tabby), and the receptor, Edar (Downless).
For example, two TS lethal mutants are known to affect protein synthesis by impairing ribosome function [9], [10].
The capsule has long been identified as a virulence factor by virtue of its antiphagocytic activity, and acapsular mutants are known to be avirulent [37].
E. coli iciA null mutants are known to be completely viable and have the same growth rate as of wild type [12].
Insertions in rsbU and rsbV eliminate SigB activity [10], and sigB mutants are known to have increased nuc gene expression [27].
At the time, UNG mutants were known to be viable in all species, and since no previous work had implicated DNA repair in CENP-A assembly, our initial report was met with skepticism.
The two genes, Apc and Siah1, which were found to be downregulated in Dll1 mutants, are known to act via β-catenin and by extension on Wnt signaling [34], [35], [70].
Because sel1-10 mutares are known to take up 80% less sulfate than their wildtype background Ws, these results mean that phytotoxic effects of magnesium sulfate on overall plant growth are dominated by the Mg2+ cation.
