Courtesy of Biosource International
is plainly visible in heart tissue from an MHC-Rac1 transgenic mouse (right), compared with its normal counterpart (left). Green, pERK 1/2 (pTEpY185/187); blue, actin; red, nuclei.
Protein phosphorylation is one of the most widely studied posttranslational modifications, with good reason. Many cellular signaling events rely on the addition or subtraction of phosphate groups (by kinases and phosphatases, respectively) to serine, threonine, and tyrosine residues.
"There are something like 500 protein kinases in the human genome, each of them phosphorylating between one and 100 substrates, and the majority of proteins in the cell can be phosphorylated under one condition or another," says Tony Hunter of the Salk Institute for Biological Studies, La Jolla, Calif. "In many cases, the effects of phosphorylation are combinatorial and multiple sites are phosphorylated, and this can have a different effect than phosphorylation of single sites." Naturally, perturbation of these events can lead ...
