InterPro domain: IPR037981

Serine/threonine-protein phosphatase PP1 ( 3.1.3.16 ) is a complex of a catalytic subunit, either PPP1CA, PPP1CB or PPP1CC, with one or more regulatory or targeting subunits. Example targeting subunits are PPP1R12A and PPP1R12C, which mediate binding of PP1 to myosin [ 1 , 2 , 3 ]; PPP1R3A, which mediates binding to glycogen in the skeletal muscle [ 4 ]; PPP1R7, [ 5 ]; PPP1R15A, which mediates binding to EIF2S1 [ 6 ]. The phosphatase associates with any one of many other regulatory proteins to form a complex that dephosphorylates a specific target protein. For example, centrosome splitting is regulated by the association of NEK2 with PP1 via the PPP1CA subunit [ 7 ], binding to ATG16L1 antagonizes casein kinase 2-mediated phosphorylation of ATG16L1 affecting the fate of cadiomyocytes [ 8 ] and association with TNF-a induces phosphorylation of FOXP3 which controls regulatory T cell function [ 9 ]. PP1 is required for the cell cycle [ 10 ], cell division, glycogen metabolism [ 11 ], muscle contraction [ 11 ] and protein synthesis. PPP1CA and PPP1CB are components of the PTW/PP1 phosphatase complex [ 11 ].

This entry includes the catalytic subunit gamma (PPP1CC) from mammals, Dis2 from fission yeasts and Glc7 from budding yeasts. Glc7 is also a component of the cleavage and polyadenylation factor (CPF) complex, which plays a key role in polyadenylation-dependent pre-mRNA 3'-end formation and cooperates with cleavage factors including the CFIA complex and NAB4/CFIB [ 12 ].

1. Myosin phosphatase: structure, regulation and function. Mol. Cell. Biochem. 259, 197-209
2. Phosphorylation of a novel myosin binding subunit of protein phosphatase 1 reveals a conserved mechanism in the regulation of actin cytoskeleton. J. Biol. Chem. 276, 21209-16
3. New roles for the LKB1-NUAK pathway in controlling myosin phosphatase complexes and cell adhesion. Sci Signal 3, ra25
4. Molecular cloning and expression of the regulatory (RG1) subunit of the glycogen-associated protein phosphatase. J. Biol. Chem. 266, 15782-9
5. Binding of the concave surface of the Sds22 superhelix to the alpha 4/alpha 5/alpha 6-triangle of protein phosphatase-1. J. Biol. Chem. 277, 47331-7
6. Growth arrest and DNA damage-inducible protein GADD34 assembles a novel signaling complex containing protein phosphatase 1 and inhibitor 1. Mol. Cell. Biol. 21, 6841-50
7. Protein phosphatase-1alpha regulates centrosome splitting through Nek2. Cancer Res. 67, 1082-9
8. ATG16L1 phosphorylation is oppositely regulated by CSNK2/casein kinase 2 and PPP1/protein phosphatase 1 which determines the fate of cardiomyocytes during hypoxia/reoxygenation. Autophagy 11, 1308-25
9. Phosphorylation of FOXP3 controls regulatory T cell function and is inhibited by TNF-α in rheumatoid arthritis. Nat. Med. 19, 322-8
10. Protein phosphatase 1 (PP1) is a post-translational regulator of the mammalian circadian clock. PLoS ONE 6, e21325
11. Identification and characterization of a novel human PP1 phosphatase complex. J. Biol. Chem. 285, 24466-76
12. Organization and function of APT, a subcomplex of the yeast cleavage and polyadenylation factor involved in the formation of mRNA and small nucleolar RNA 3'-ends. J. Biol. Chem. 278, 33000-10