Title: Phosphoprotein Inhibitors of Protein Phosphatase-1
Abstract: The chapter discusses phosphoprotein inhibitors of protein phosphatase-1(PP1). Over 25 years ago, a search for proteins that could regulate phosphorylase phosphatase yielded heat-stable proteins that were called “inhibitor-1” (I-1) and “inhibitor-2” (I-2). I-1 potency as an inhibitor increased several hundred-fold after phosphorylation of Thr35 by cAMP-dependent protein kinase (PKA), whereas inhibitor-2 was effective without prior phosphorylation. Inhibitor-1 became the prototype for other phosphoprotein inhibitors of PP1. To distinguish protein phosphates in type-1 (PP1, sensitive to inhibitors) from type-2, these inhibitor proteins are made use of subsequently.. Several new PP1 inhibitor phosphoproteins, such as NIPP-1, inhibitor-4, CPI-17, PHI-1 and KEPI have been discovered in mammalian cells. Regulation of PP1 in cells incorporates the various inhibitor phosphoproteins to selectively target a subset of PP1 holoenzymes. This way the inhibitor proteins work in concert with the PP1 regulatory subunits. Study of the phosphorylation of the PP1 inhibitors takes on added significance for understanding signaling processes, and the chapter describes various methods developed for that purpose.
Publication Year: 2003
Publication Date: 2003-01-01
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
Access and Citation
Cited By Count: 10
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