Selective targeting of the γ1 isoform of protein phosphatase 1 to F-actin in intact cells requires multiple domains in spinophilin and neurabin
Selective targeting of the γ1 isoform of protein phosphatase 1 to F-actin in intact cells requires multiple domains in spinophilin and neurabin
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DOI：
10.1096/fj.07-092841
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发表时间：
2008-06-01
期刊：
影响因子：
4.8
通讯作者：
Colbran, Roger J.
中科院分区：
文献类型：
--
作者：
Carmody, Leigh C.;Baucum, Anthony J., II;Colbran, Roger J.
蛋白磷酸酶1 （PP1）催化亚基在离散的亚细胞区室中去磷酸化特定的底物，以调节许多细胞过程。典型PP1结合基序（R/K-V/I-X-F）在一个蛋白家族中介导亚细胞靶向，并且在所有PP1同工异构体中形成典型基序结合袋的氨基酸是相同的。然而，PP1 γ - 1而非PP1 β选择性定位于神经元中富含f -肌动蛋白的树突棘。尽管f -肌动蛋白结合蛋白neurabin I和spinophilin （neurabin II）也结合PP1，但它们在完整细胞中PP1异构体选择性靶向中的作用尚不清楚。我们在这里表明，嗜脊髓蛋白选择性地靶向PP1 γ - 1，而不是PP1 β，到完整细胞富含f -肌动蛋白的皮质区域。嗜spinophilin中PP1 γ 1选择性决定因子(N（464)EDYDRR(470)：在神经素中作为残基473 -479保守）向VKDYDTW突变严重减弱PP1 γ 1与神经素在体外和细胞内的相互作用，并破坏PP1 γ 1靶向F-actin。该结构域不参与神经素与PP1 β的弱相互作用。相反，典型的pp1结合基序的突变减弱了神经素与这两种亚型的相互作用。因此，神经抑制素在完整细胞中选择性地将PP1 γ 1靶向f -肌动蛋白，既需要典型的PP1结合基序，也需要辅助的PP1 γ 1选择性决定因素。
Protein phosphatase 1 (PP1) catalytic subunits dephosphorylate specific substrates in discrete subcellular compartments to modulate many cellular processes. Canonical PP1-binding motifs (R/K-V/I-X-F) in a family of proteins mediate subcellular targeting, and the amino acids that form the binding pocket for the canonical motif are identical in all PP1 isoforms. However, PP1 gamma 1 but not PP1 beta is selectively localized to F-actin-rich dendritic spines in neurons. Although the F-actin-binding proteins neurabin I and spinophilin (neurabin II) also bind PP1, their role in PP1 isoform selective targeting in intact cells is poorly understood. We show here that spinophilin selectively targets PP1 gamma 1, but not PP1 beta, to F-actin-rich cortical regions of intact cells. Mutation of a PP1 gamma 1 selectivity determinant (N(464)EDYDRR (470) in spinophilin: conserved as residues 473 -479 in neurabin) to VKDYDTW severely attenuated PP1 gamma 1 interactions with neurabins in vitro and in cells and disrupted PP1 gamma 1 targeting to F-actin. This domain is not involved in the weaker interactions of neurabins with PP1 beta. In contrast, mutation of the canonical PP1-binding motif attenuated interactions of neurabins with both isoforms. Thus, selective targeting of PP1 gamma 1 to F-actin by neurabins in intact cells requires both the canonical PP1-binding motif and an auxiliary PP1 gamma 1-selectivity determinant.