Antibodies to Protein Phosphatase 2 family - FocusOn 039

Introduction: Protein phosphorylation is dependent on the opposing actions of protein kinases and protein phosphatases. Four major protein phosphatases have been identified in the cytosol of eukaryotic cells which are responsible for the dephosphorylation of serine and threonine residues in proteins. Although all 4 protein phosphatases, PP1, PP2A, PP2B, and PP2C, have overlapping substrate specificities in vitro, they can be distinguished by the use of inhibitor proteins and by their dependence on metal ions.

Protein Phosphatase 2A

Protein phosphatase 2A (PP2A) is the most abundant phosphatase specific for serine and threonine phosphorylation in mammalian cells. Dephosphorylation of substrates targeted by PP2A plays a vital role in a large variety of cellular processes including signal transduction, regulation of the cell cycle, gene expression and development. Protein phosphatase 2 is one of the four major Ser/Thr phosphatases, and it is implicated in the negative control of cell growth and division. It consists of a common heteromeric core enzyme, which is composed of a catalytic subunit and a constant regulatory subunit, that associates with a variety of regulatory subunits. The constant regulatory subunit alpha serves as a scaffolding molecule to coordinate the assembly of the catalytic subunit and a variable regulatory beta subunit.

Fig.1: Cat.-No. AP19055PU-N PPP2CA antibody staining of Methanol-fixed HeLa at 1/200 dilution.

Fig.2: Cat.-No. AP15290PU-N PPP2CA/PPP2CB antibody staining of Formalin-Fixed Paraffin-Embedded Human cancer tissue followed by peroxidase conjugated secondary antibody and DAB staining.

Fig.3: Cat.-No. AP05040PU-N PPP2R1A antibody staining of total Rat brain homogenate.

Fig.4: Cat.-No. AP08886PU-N PPP2R3A antibody staining of Formalin-Fixed, Paraffin-Embedded Human Brain, cerebellum at 5 µg/ml followed by biotinylated anti-goat IgG secondary antibody, alkaline phosphatase-streptavidin and chromogen.

Protein Phosphatase 2B

Calmodulin-dependent protein phosphatase, calcineurin or Protein Phosphatase 2B, is involved in a wide range of biologic activities, acting as a Ca(2+)-dependent modifier of phosphorylation status. In testis, the motility of the sperm is thought to be controlled by cAMP-dependent phosphorylation and a unique form of calcineurin appears to be associated with the flagellum. The calcineurin holoenzyme is composed of catalytic and regulatory subunits of 60 and 18 kD, respectively. At least 3 genes, calcineurin A-alpha (PPP3CA), calcineurin A-beta (PPP3CB), and calcineurin A-gamma (CALNA3 or PPP3CC), have been cloned for the catalytic subunit. These genes have been identified in humans, mice, and rats, and are highly conserved between species (90 to 95% amino acid identity).

Fig.5: Cat.-No. AP15297PU-N PPP3CC antibody staining of Formalin-Fixed Paraffin-Embedded Human cancer tissue, followed by peroxidase conjugated secondary antibody and AEC staining.

Fig.6: Cat.-No. AP09004PU-N PPP3R1 antibody staining of Formalin-Fixed Paraffin-Embedded Human Tonsil at 5 µg/ml followed by biotinylated Goat anti-Rabbit IgG secondary antibody, alkaline phosphatase-streptavidin and chromogen.

Protein Phosphatase 2C

PPM1A is a member of the PP2C family of Ser/Thr protein phosphatases. PP2C family members are known to be negative regulators of cell stress response pathways. This phosphatase dephosphorylates, and negatively regulates the activities of, MAP kinases and MAP kinase kinases. It has been shown to inhibit the activation of p38 and JNK kinase cascades induced by environmental stresses. This phosphatase can also dephosphorylate cyclin-dependent kinases, and thus may be involved in cell cycle control. Overexpression of this phosphatase is reported to activate the expression of the tumor suppressor gene TP53/p53, which leads to G2/M cell cycle arrest and apoptosis.

Protein phosphatase 1B (PPM1B) is a member of the PP2C family of serine/threonine protein phosphatases. PP2C family members are known to be negative regulators of cell stress response pathways. This phosphatase has been shown to dephosphorylate cyclin-dependent kinases, and thus may be involved in cell cycle control. Overexpression of this phosphatase is reported to cause cell-growth arrest or cell death.

PPM1G (Protein phosphatase 1G) is a member of the PP2C family of Serine/threonine protein phosphatases. PP2C family members are known to be negative regulators of cell stress response pathways. The human Ser/Thr phosphatase PPM1G promotes spliceosome assembly. This phosphatase is found to be responsible for the dephosphorylation of Pre-mRNA splicing factors, which is important for the formation of functional spliceosome.

PPM1M is a member of the PP2C family of Ser/Thr protein phosphatases. PP2C family members are known to be negative regulators of cell stress response pathways. This phosphatase was identified as an interacting protein of Rho guanine nucleotide exchange factors (PIX). PIX proteins are regulators of p21/Cdc42/Rac1-activated kinase 1 (PAK1), a protein kinase mediating biological effects downstream of Rho GTPases. This phosphatase has been shown to block the effects of PAK, and thus inhibit actin stress fiber breakdown and morphological changes driven by cell division cycle 42 (CDC42).

PPM1D is a member of the PP2C family of Ser/Thr protein phosphatases. PP2C family members are known to be negative regulators of cell stress response pathways. Expression of this PPM1D gene is induced in a p53-dependent manner in response to various environmental stresses. While being induced by tumor suppressor protein TP53/p53, this phosphatase negativelyregulates the activity of p38 MAP kinase, MAPK/p38, through which it reduces the phosphorylation of p53, and in turn suppresses p53-mediated transcription and apoptosis. This phosphatase thus mediates a feedback regulation of p38-p53 signaling that contributes to growth inhibition and the suppression of stressinduced apoptosis. The PPM1D gene is located in a chromosomal region known to be amplified in breast cancer. The amplification of this gene has been detected in both breast cancer cell line and primary breast tumors, which suggests a role of this gene in cancer development.

Fig.7: Cat.-No. AP15299PU-N PP2C alpha/PPM1A antibody staining of Mouse kidney tissue lysate (35 µg/lane). PPM1A (arrow) was detected using the purified antibody (1/60 dilution).

Fig.8: Cat.-No. AP15301PU-N PP2C beta/PPM1B antibody staining of Mouse kidney tissue lysate at 35 µg (Right). AP15301PU-N PP2C beta/PPM1B antibody pre-incubated with and without Blocking Peptide in 293 cell line lysate (Left).

Fig.9: Cat.-No. AP15301PU-N PP2C beta/PPM1B antibody staining of Formalin-Fixed Paraffin-Embedded Human cancer tissue followed by peroxidase conjugated secondary antibody and AEC staining.

Available Antibodies to Protein Phosphatase 2 family