Protein Phosphatase

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Protein phosphatase is a type of enzyme molecule that catalyzes the dephosphorylation reaction of phosphorylated protein molecules. It exists corresponding to protein kinases, and together constitutes the switch system of phosphorylation and dephosphorylation, an important protein activity.

Classification

The role of protein phosphatase is opposite to that of protein kinase. According to the different amino acid residues that are dephosphorylated, protein phosphatases are also divided into protein tyrosine phosphatase (PTP, PTPase) and serine/threonine phosphatase.

The protein phosphatases involved in lymphocyte activation mainly include:

①CD45: The two domains of the intracellular segment of the molecule play the role of PTP, so CD45 belongs to the receptor type protein tyrosine phosphatase, which plays a key role in resisting kPTK and initiating lymphocyte signal transduction;

②Calcineurin is a serine/threonine phosphatase whose substrate is the phosphorylated serine and threonine residues of the transcription factor NF-AT molecule. Under the action of calcineurin, NF-ATp is activated by dephosphorylation (p) and becomes the activated transcription factor NF-AT.

Examples

Protein Phosphatase 1 (PP1)

Protein Phosphatase 1 (PP1) is a major eukaryotic protein serine/threonine phosphatase, which can interact with more than fifty different established or putative regulatory subunits through its catalytic subunit (PP1c) Interaction to regulate a variety of cell functions. Most of these target PP1c to specific subcellular locations and interact with small hydrophobic grooves on the surface of PP1c through the short conservative binding motif RVxF motif, which is usually other basic residues first.

Figure 1. Protein structure of PP1.

PPP1CB

The catalytic subunit of serine/threonine protein phosphatase PP1-β is an enzyme encoded by the PPP1CB gene in the human body. The protein encoded by this gene is one of the three catalytic subunits of protein phosphatase 1 (PP1). PP1 is a serine/threonine specific protein phosphatase, which is known to be involved in the regulation of various cellular processes, such as cell division, glycogen metabolism, muscle contraction, protein synthesis and HIV-1 virus transcription.

Figure 2. Protein structure of PPP1CB.

Functions

Phosphatase is the opposite of kinase/phosphatase, which adds phosphate groups to proteins. The addition of phosphate groups can activate or inactivate enzymes (eg, kinase signaling pathways) or allow protein-protein interactions to occur. Therefore, phosphatase is essential for many signal transduction pathways. The addition and removal of phosphoric acid does not necessarily correspond to the activation or inhibition of enzymes, and several enzymes have separate phosphorylation sites for activating or inhibiting functional regulation. For example, depending on the specific amino acid residue that is phosphorylated, CDK can be activated or inactivated. Phosphates are important in signal transduction because they regulate the proteins connected to them. In order to reverse the regulation, phosphate is removed. It occurs through hydrolysis itself, or is mediated by protein phosphatase. Protein phosphorylation plays a vital role in biological functions and controls almost every cellular process, including metabolism, gene transcription and translation, cell cycle progression, cytoskeletal rearrangement, protein-protein interaction, and protein stability Sex, cell movement and apoptosis. These processes depend on changes in the phosphorylation of key proteins, leading to highly regulated and opposite effects of PK and PP. Phosphorylation of histones, as well as methylation, ubiquitination, SUMOylation and acetylation, also regulate access to DNA through chromatin reorganization.