It turns out that your classic experimental trick to mimic protein phosphorylation by mutating serines and threonines to aspartate or glutamate at phosphorylation sites was not first discovered by humans. Pearlman, Serber and Ferrell argue that many phosphorylation sites in proteins evolved from negatively charged amino acid residues, which means that phosphorylation evolved to mimic the effects of glutamate and aspartate. This, of course, occurred long before human scientists discovered in 1987 that you could replace phosphorlated serines and threonines with negatively charged amino acids and still get a functional protein.
“A Mechanism for the Evolution of Phosphorylation Sites”, Samuel M. Pearlman, Zach Serber, James E. Ferrell Jr., Cell Volume 147, Issue 4, 11 November 2011, Pages 934–946 Continue reading
