Western blot analysis of the phosphorylated proteins with UV-treated cell lysates mouse spleen cell.  Bands are responsive to treatment with varying long UV wavelengths: A(0), B(50), C(200), D(400), and E (treated with 0.1μM okadaic acid).

Protein phosphorylation is an important posttranslational modification that serves many key functions to regulate a protein’s activity, localization, and protein-protein interactions. Phosphorylation is catalyzed by various specific protein kinases, which involves removing a phosphate group from ATP and covalently attaching it to to a recipient protein that acts as a substrate. Most kinases act on both serine and threonine; others act on tyrosine, and a number (dual specificity kinases) act on all three. Because phosphorylation can occur at multiple sites on any given protein, it can therefore change the function or localization of that protein at any time (1). Changing the function of these proteins has been linked to a number of diseases, including cancer, diabetes, heart disease, inflammation and neurological disorders (2-4).

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5. Ostrovsky PC. (1995). Genes Dev. 9(16): 2034-2041.