Protein phosphatase 1
| protein phosphatase 1, catalytic subunit, alpha isozyme | |
|---|---|
| Identifiers | |
| Symbol | PPP1CA |
| Alt. symbols | PP1, PP1a, MGC15877, MGC1674, PP-1A, PP1alpha, PPP1A |
| Entrez | 5499 |
| HUGO | 9281 |
| OMIM | 176875 |
| RefSeq | NP_002699.1 |
| UniProt | P62136 |
| Other data | |
| EC number | 3.1.3.16 |
| Locus | Chr. 11 q13 |
| protein phosphatase 1, catalytic subunit, beta isozyme | |
|---|---|
| Identifiers | |
| Symbol | PPP1CB |
| Alt. symbols | PP1, PP1b, PP1beta, PP-1B; PPP1CD; MGC3672; PP1beta; PPP1CB |
| Entrez | 5500 |
| HUGO | 9282 |
| OMIM | 600590 |
| RefSeq | NP_002700.1 |
| UniProt | P62140 |
| Other data | |
| EC number | 3.1.3.16 |
| Locus | Chr. 2 p23 |
| protein phosphatase 1, catalytic subunit, gamma isozyme | |
|---|---|
| Identifiers | |
| Symbol | PPP1CC |
| Alt. symbols | PP1gamma, PP1y, PP1gamma, PPP1G |
| Entrez | 5501 |
| HUGO | 9283 |
| OMIM | 176914 |
| RefSeq | NP_002701.1 |
| UniProt | P36873 |
| Other data | |
| EC number | 3.1.3.16 |
| Locus | Chr. 12 q24 |
Protein phosphatase 1 (PP1) belongs to a certain class of phosphatases known as protein serine/ threonine phosphatases. This type of phosphatase includes metal-dependent protein phosphatases (PPMs) and aspartate-based phosphatases. PP1 has been found to be important in the control of glycogen metabolism, muscle contraction, cell progression, neuronal activities, splicing of RNA, mitosis, cell division, apoptosis, protein synthesis, and regulation of membrane receptors and channels.
Each PP1 enzyme contains both a catalytic subunit and a regulatory subunit. The catalytic subunit consists of a 30-kD single-domain protein that can form complexes with other regulatory subunits. The catalytic subunit is highly conserved among all eukaryotes, thus suggesting a common catalytic mechanism. The catalytic subunit can from complexes with various regulatory subunits. These regulatory subunits play an important role in substrate specificity as well as compartmentalization. Some common regulatory subunits include GM and GL, which are named after their locations of action within the body (Muscle and Liver respectively).
X-ray crystallographic structural data is available for PP1 catalytic subunit. The catalytic subunit of PP1 forms an α/β fold with a central β-sandwich arranged between two α-helical domains. The interaction of the three β-sheets of the β-sandwich creates a channel for catalytic activity, as it is the site of coordination of metal ions. These metal ions have been identified as Mn and Fe and their coordination is provided by three histidines, two aspartic acids, and one asparagine.
The mechanism involves two metal ions binding and activating water, which initiates a nucleophilic attack on the phosphorus atom.
Regulation of these different processes is performed by distinct PP1 holoenzymes that facilitate the complexation of the PP1 catalytic subunit to various regulatory subunits.
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Wikipedia