Protein phosphatase (PP (generic; specific isoforms include PP1, PP2A, PP2B, etc.))

Protein phosphatase refers to a large superfamily of enzymes that catalyze the removal of a phosphate group from phosphorylated proteins—a critical process for the regulation of cellular signaling. Protein phosphatases counterbalance the actions of protein kinases, maintaining cell homeostasis through reversible phosphorylation. They are broadly classified by substrate specificity and structural features into serine/threonine phosphatases (PPP, PPM, Asp-based), tyrosine phosphatases (PTP), and dual-specific phosphatases. Prominent members include protein phosphatase 1 (PP1), protein phosphatase 2A (PP2A), protein phosphatase 2B (calcineurin/PP2B), and protein phosphatase 2C (PP2C/PPM1). They play essential roles in cell cycle progression, apoptosis, cell signaling, and stress responses. Dysfunction or dysregulation of specific protein phosphatases is implicated in cancer, neurodegeneration, cardiovascular diseases, and other pathologies[1][3][5]. Due to their central roles, select protein phosphatases—especially calcineurin—are important drug targets (e.g., by immunosuppressants such as cyclosporine and tacrolimus), but the broad and highly conserved nature of these enzyme families poses challenges for therapeutic specificity and safety[3][5][8]. **Important caveat:** "Protein phosphatase" as a target is a superfamily name and lacks specificity. Research, clinical targeting, and biomarker applications typically relate to individual isoforms (e.g., PP2A, PP1, calcineurin/PP2B, PPM1D), each with distinct biology and pharmacology. Therefore, this entry is too general for drug development or biomarker strategies. A more specific target, such as "Protein phosphatase 2A," should be used for structured annotation or therapeutic purposes[1][2][4][6].

Other names

phosphoprotein phosphataseserine/threonine phosphatasetyrosine phosphataseprotein phosphatase 1 (PP1)protein phosphatase 2A (PP2A)protein phosphatase 2B (PP2B/calcineurin)protein phosphatase 2C (PP2C)PPM1PPP

Inhibition of phosphatase activity (immunosuppression by calcineurin inhibition, toxin-induced phosphatase inhibition, etc.) Modulation of cell signaling by altering protein phosphorylation state