phosphatases(磷酸酶)

Phosphatases are enzyme that remove a phosphate group from a protein. Protein tyrosine phosphatases (PTPs) comprise a diverse family of transmembrane and cytoplasmic enzymes. PTPs play an important role in regulating the proliferative activity of cells and the integrity of cell-cell and cell-matrix contacts. Protein tyrosine phosphatase 1B (PTP1B) is a non-receptor PTP frequently associated with the endoplasmic reticulum and vesicles subjacent to the plasma membrane. PTP1B as a key negative regulator of leptin receptor pathways has been an attractive therapeutic target for the treatment of type 2 diabetes mellitus and obesity. Four major serine/threonine-specific protein phosphatase catalytic subunits are present in the cytoplasm of animal cells. Three of these enzymes, PP1, PP2A, and PP2B, are members of the same gene family, while PP2C appears to be distinct.The alkaline phosphatases comprise a heterogeneous group of enzymes that are widely distributed in mammalian cells. Acid phosphatase enzymes catalyze the hydrolysis of phosphate monoesters following the general equation.