Ulloa L, Dombrádi V, Díaz-Nido J, Szücs K, Gergely P, Friedrich P, Avila J
Centro de Biología Molecular (CSIC-UAM), Universidad Autónoma de Madrid, Spain.
FEBS Lett. 1993 Sep 6;330(1):85-9. doi: 10.1016/0014-5793(93)80925-k.
Rat brain microtubule-associated protein MAP1B has been tested as a substrate for Ser/Thr protein phosphatases (PP). The dephosphorylation reactions were followed by specific antibodies recognizing phosphorylated and phosphorylatable epitopes. One set of phosphorylation sites on MAP1B are referred to as mode I sites, and their phosphorylation is presumably catalyzed by proline-directed protein kinases. These mode I sites are efficiently dephosphorylated by PP2B and 2A but not by PP1. Another set of phosphorylation sites on MAP1B are named mode II sites, and their phosphorylation is possibly due to casein kinase II. These mode II sites are dephosphorylated by PP2A and PP1, the PP2B being ineffective. The selectivity of phosphatases for different sites within the same protein indicates the complexity of the dephosphorylation reactions regulating the functionality of MAP1B in neurons.
大鼠脑微管相关蛋白MAP1B已被用作丝氨酸/苏氨酸蛋白磷酸酶（PP）的底物进行测试。去磷酸化反应通过识别磷酸化和可磷酸化表位的特异性抗体进行跟踪。MAP1B上的一组磷酸化位点被称为I型位点，其磷酸化大概由脯氨酸导向蛋白激酶催化。这些I型位点可被PP2B和2A有效去磷酸化，但不能被PP1去磷酸化。MAP1B上的另一组磷酸化位点被命名为II型位点，其磷酸化可能归因于酪蛋白激酶II。这些II型位点可被PP2A和PP1去磷酸化，而PP2B则无效。磷酸酶对同一蛋白质内不同位点的选择性表明了调节神经元中MAP1B功能的去磷酸化反应的复杂性。
