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Selective targeting of the γ1 isoform of protein phosphatase 1 to F‐actin in intact cells requires multiple domains in spinophilin and neurabin
Author(s) -
Carmody Leigh C.,
Baucum Anthony J.,
Bass Martha A.,
Colbran Roger J.
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.07-092841
Subject(s) - gene isoform , protein phosphatase 1 , actin , phosphatase , microbiology and biotechnology , biology , hek 293 cells , subcellular localization , dendritic spine , chemistry , biochemistry , phosphorylation , gene , cytoplasm , hippocampal formation , neuroscience
Protein phosphatase 1 (PP1) catalytic subunits dephosphorylate specific substrates in discrete subcellular compartments to modulate many cellular processes. Canonical PPl‐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, PPlγ1 but not PP1β 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 PP1γ1, but not PP1β, to F‐actin‐rich cortical regions of intact cells. Mutation of a PP1γ1 selectivity determinant (N 464 EDYDRR 470 in spinophilin: conserved as residues 473–479 in neurabin) to VKDYDTW severely attenuated PP1γ1 interactions with neurabins in vitro and in cells and disrupted PP1γ1 targeting to F‐actin. This domain is not involved in the weaker interactions of neurabins with PP1γ. In contrast, mutation of the canonical PP1‐binding motif attenuated interactions of neurabins with both isoforms. Thus, selective targeting of PP1γ1 to F‐actin by neurabins in intact cells requires both the canonical PP1‐binding motif and an auxiliary PP1γ1‐selectivity determinant.— Carmody L. C., IIBaucum A. J., Bass, M. A., Colbran R.J. Selective targeting of the γ1 isoform of protein phosphatase 1 to F‐actin in intact cells requires multiple domains in spinophilin and neurabin. FASEB J. 22, 1660–1671 (2008)