Bollen M, Stalmans W
Afdeling Biochemie, Fakulteit Geneeskunde, Katholieke Universiteit Leuven, Belgium.
Crit Rev Biochem Mol Biol. 1992;27(3):227-81. doi: 10.3109/10409239209082564.
Type 1 protein phosphatases (PP-1) comprise a group of widely distributed enzymes that specifically dephosphorylate serine and threonine residues of certain phosphoproteins. They all contain an isoform of the same catalytic subunit, which has an extremely conserved primary structure. One of the properties of PP-1 that allows one to distinguish them from other serine/threonine protein phosphatases is their sensitivity to inhibition by two proteins, termed inhibitor 1 and inhibitor 2, or modulator. The latter protein can also form a 1:1 complex with the catalytic subunit that slowly inactivates upon incubation. This complex is reactivated in vitro by incubation with MgATP and protein kinase FA/GSK-3. In the cell the type 1 catalytic subunit is associated with noncatalytic subunits that determine the activity, the substrate specificity, and the subcellular location of the phosphatase. PP-1 plays an essential role in glycogen metabolism, calcium transport, muscle contraction, intracellular transport, protein synthesis, and cell division. The activity of PP-1 is regulated by hormones like insulin, glucagon, alpha- and beta-adrenergic agonists, glucocorticoids, and thyroid hormones.
1型蛋白磷酸酶（PP-1）是一组分布广泛的酶，它们能特异性地使某些磷蛋白的丝氨酸和苏氨酸残基去磷酸化。它们都含有相同催化亚基的一种同工型，其一级结构极其保守。PP-1区别于其他丝氨酸/苏氨酸蛋白磷酸酶的特性之一是它们对两种蛋白质（称为抑制剂1和抑制剂2或调节剂）的抑制作用敏感。后一种蛋白质也能与催化亚基形成1:1复合物，该复合物在孵育时会缓慢失活。通过与MgATP和蛋白激酶FA/GSK-3一起孵育，这种复合物在体外可被重新激活。在细胞中，1型催化亚基与非催化亚基相关联，这些非催化亚基决定了磷酸酶的活性、底物特异性和亚细胞定位。PP-1在糖原代谢、钙转运、肌肉收缩、细胞内运输、蛋白质合成和细胞分裂中起重要作用。PP-1的活性受胰岛素、胰高血糖素、α和β肾上腺素能激动剂、糖皮质激素和甲状腺激素等激素的调节。
