Phosphatase Subfamily PPP1C

Phosphatase Classification: Fold MTDP: Superfamily MTDP: Family PPP: Subfamily PPP1C (PP1)

PPP1C is a ubiquitous serine/threonine phosphatase found throughout eukaryotes and even in some prokaryotes. By forming complexes with different regulatory subunits, it is involved in many various processes.

Evolution

PPP1C subfamily is found throughout eukaryotes even in some prokaryotes. It has many lineage-specific gene duplications. In particular, 10 PPP1Cs are found in fruit fly, 3 in human, 3 in C. elegans, and 4 in yeast.

Domain

PPP1C has a single domain - phosphatase domain.

Functions

The PPP1C subfamily is the catalytic subunit of PP1 holoenzyme binding to regulatory subunits to achieve diverse functions [1]. Over 50 different regulatory subunits are known in human and at least 20 in yeast. These different complexes play key roles in various cellular processes, such as cell cycle progression [2] and glycogen metabolism. Below are some examples:

PPP1C, in complex with regulatory subunits, dephosphorylates the substrates below:

• Myosin (light chain). PPP1C forms myosin-light-chain phosphatase (MLCP) in complex with PPP1R12A (MYPT1/M130) and PPP1R12A (M20).

• eIF2α. PPP1C-PPP1R15A (GADD34) holophosphatase in complex with G-actin, dephosphorylates the alpha subunit of eukaryotic translation initiation factor 2 (eIF2α) and inhibits integrated stress response (ISR) [3, 4, 5].

PPP1C, in complex with its regulatory subunit NIPP1, activates mesenchymal genes in HeLa cells, though its substrates in this biological process are unclear [6].

Regulatory subunits

PPP1R15B

A missense mutation in PPP1R15B causes a syndrome including diabetes, short stature and microcephaly [7].

References

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