Overview of protein phosphorylation.
Phosphorylation is the most common and important mechanism of acute and reversible regulation of protein function. Studies of mammalian cells metabolically labeled with [(32)P]orthophosphate suggest that as many as one-third of all cellular proteins are covalently modified by protein phosphorylation. Protein phosphorylation has an important role in essentially all aspects of cell biology. Most polypeptide growth factors (platelet-derived growth factor and epidermal growth factor are among the best studied) and cytokines (e.g., interleukin 2, colony stimulating factor 1, and gamma-interferon) stimulate phosphorylation upon binding to their receptors. Induced phosphorylation in turn activates cytoplasmic protein kinases, such as Raf, the activators of the mitogen-activated protein (MAP) kinases SEK and MEK, the MAP kinases ERK, JNK, and p38, the Janus/JAK kinases, the p21 activated kinases (PAKs), and the phosphatidylinsoitil 3'-kinase-activated kinase, protein kinase B/Akt. Additionally, in all nucleated organisms, cell cycle progression is regulated at both the G1/S and the G2/M transitions by cyclin-dependent protein kinases. These kinases regulate the G1/S transition by the phosphorylation of cell cycle regulators such as Rb protein and the G2/M transition through the phosphorylation of nuclear lamins and histones.
Sefton
B M
BM
The Salk Institute, San Diego, California, USA.
D000818:Animals; D006801:Humans; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*
D011506:Proteins; D011494:Protein Kinases; D010749:Phosphoprotein Phosphatases