Protein phosphatase 2A: the Trojan Horse of cellular signaling

Dynamic phosphorylation and dephosphorylation of proteins are fundamental m echanisms utilized by cells to transduce signals. Whereas transduction by p rotein kinases has been a major focus of studies in the last decade, protei n phosphatase 2A (PP2A) enzymes emerge in this millenium as the most fashio nable players in cellular signaling. Viral proteins target specific PP2A en zymes in order to deregulate chosen cellular pathways in the host and promo te viral progeny. The observation that a variety of viruses utilize PP2A to alienate cellular behavior emphasizes the fundamental importance of PP2A i n signal transduction. This review will primarily focus an discussing the u niqueness of PP2A regulation and uncovering the critical role played by pro tein-protein interactions in the modulation of PP2A signaling. Moreover, th e place of PP2A in signaling pathways and its functional significance for h uman diseases will be discussed. (C) 2001 Elsevier Science Inc. All rights reserved.