A protein phosphatase is a phosphatase enzyme that removes a phosphate group from the phosphorylated amino acid residue of its substrate protein. Protein phosphorylation is one of the most common forms of reversible protein posttranslational modification (PTM), with up to 30% of all proteins being phosphorylated at any given time. Protein kinases (PKs) are the effectors of phosphorylation and catalyse the transfer of a γ-phosphate from ATP to specific amino acids on proteins. Several hundred PKs exist in mammals and are classified into distinct super-families. Proteins are phosphorylated predominantly on Ser, Thr and Tyr residues, which account for 79.3, 16.9 and 3.8% respectively of the phosphoproteome, at least in mammals. In contrast, protein phosphatases (PPs) are the primary effectors of dephosphorylation and can be grouped into three main classes based on sequence, structure and catalytic function. The largest class of PPs is the phosphoprotein phosphatase (PPP) family comprising PP1, PP2A, PP2B, PP4, PP5, PP6 and PP7, and the protein phosphatase Mg2+- or Mn2+-dependent (PPM) family, composed primarily of PP2C. The protein Tyr phosphatase (PTP) super-family forms the second group, and the aspartate-based protein phosphatases the third. The protein pseudophosphatases form part of the larger phosphatase family, and in most cases are thought to be catalytically inert, instead functioning as phosphate-binding proteins, integrators of signalling or subcellular traps. Examples of membrane-spanning protein phosphatases containing both active (phosphatase) and inactive (pseudophosphatase) domains linked in tandem are known, conceptually similar to the kinase and pseudokinase domain polypeptide structure of the JAK pseudokinases. A complete comparative analysis of human phosphatases and pseudophosphatases has been completed by Manning and colleagues, forming a companion piece to the ground-breaking analysis of the human kinome, which encodes the complete set of ~536 human protein kinases.
Protein kinase C delta type is an enzyme that in humans is encoded by the PRKCD gene.
Histone H3.1t is a protein that in humans is encoded by the HIST3H3 gene.
Calcium/calmodulin-dependent protein kinase type IV is an enzyme that in humans is encoded by the CAMK4 gene.
Proto-oncogene tyrosine-protein kinase Yes is a non-receptor tyrosine kinase that in humans is encoded by the YES1 gene.
Histone H2B type 2-E is a protein that in humans is encoded by the HIST2H2BE gene.
Dual specificity tyrosine-phosphorylation-regulated kinase 1A is an enzyme that in humans is encoded by the DYRK1A gene. Alternative splicing of this gene generates several transcript variants differing from each other either in the 5' UTR or in the 3' coding region. These variants encode at least five different isoforms.
Serine/threonine-protein kinase Sgk3 is an enzyme that in humans is encoded by the SGK3 gene.
Serine/threonine-protein kinase D3 (PKD3) or PKC-nu is an enzyme that in humans is encoded by the PRKD3 gene.
PITSLRE serine/threonine-protein kinase CDC2L1 is an enzyme that in humans is encoded by the CDC2L1 gene.
Calcium/calmodulin-dependent protein kinase type 1 is an enzyme that in humans is encoded by the CAMK1 gene.
Serine/threonine-protein kinase MARK1 is an enzyme that in humans is encoded by the MARK1 gene.
Phosphorylase b kinase gamma catalytic chain, skeletal muscle isoform is an enzyme that in humans is encoded by the PHKG1 gene.
Tyrosine-protein kinase BLK, also known as B lymphocyte kinase, is a non-receptor tyrosine kinase that in humans is encoded by the BLK gene. It is of the Src family of tyrosine kinases.
Dual specificity tyrosine-phosphorylation-regulated kinase 1B is an enzyme that in humans is encoded by the DYRK1B gene.
Dual specificity protein phosphatase 16 is an enzyme that in humans is encoded by the DUSP16 gene.
Diacylglycerol kinase delta is an enzyme that in humans is encoded by the DGKD gene.
WD repeat-containing protein 68 is a protein that in humans is encoded by the DCAF7 gene.
Calcium-binding tyrosine phosphorylation-regulated protein is a protein that in humans is encoded by the CABYR gene.
Dual specificity tyrosine-phosphorylation-regulated kinase 3 is an enzyme that in humans is encoded by the DYRK3 gene.
