Protein phosphatase 1 belongs to the phosphoprotein phosphatase (PPP) family of phosphatases and is involved in the regulation of a wide variety of cellular processes ranging from intermediary metabolism to apoptosis. It is estimated that almost 300 serine/threonine kinases are encoded by the human genome but only some two-dozen catalytic subunits of serine/threonine protein phosphatases. The question of how such a limited number of protein phosphatases can dephosphorylate the myriad of cellular phosphoproteins in a specific and regulated manner appears to be satisfied by the existence of a multitude of regulatory/targeting subunits. This chapter is limited to mammalian PP1-binding subunits and explains how they can account for the pleiotropic functions of the enzyme in the cell. It also takes into account some other recent reviews on this topic. It suggests that all forms of PP1 holoenzymes contain a similar, highly conserved catalytic subunit but differ in the associated regulatory subunits. The large number of associating proteins provides compelling evidence that the distinctive features of different PP1 holoenzymes reside in the regulatory components. Thus, functionally distinct forms are generated by a combination of a similar catalytic component with different regulatory subunits that are responsible for targeting the enzyme to specific cellular locales, for conferring substrate specificity, or for controlling the enzyme activity. The large number of targeting/ regulatory subunits of PP1 can thus account for the pleiotropic function of the type 1 phosphatase in the cell.
|Original language||English (US)|
|Title of host publication||Handbook of Cell Signaling, 2/e|
|Number of pages||9|
|State||Published - Dec 1 2010|
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)