title: Protein phosphatase 4 interacts with the Survival of Motor Neurons complex and enhances the temporal localisation of snRNPs.
abstract: Protein phosphatase 4 (PPP4) is a ubiquitous essential protein serine/threonine phosphatase found in higher eukaryotes. Coordinate variation of the levels of the catalytic subunit (PPP4c) and the regulatory subunit (R2) suggests that PPP4c and R2 form a heterodimeric core to which other regulatory subunits bind. Two proteins that specifically co-purify with Flag-epitope-tagged R2 expressed in HEK-293 cells were identified as Gemin3 and Gemin4. These two proteins have been identified previously as components of the Survival of Motor Neurons (SMN) protein complex, which is functionally defective in the hereditary disorder spinal muscular atrophy. Immuno-sedimentation of the epitope-tagged SMN protein complex from HeLa cells expressing CFP-SMN showed that the SMN protein interacts, as previously reported, with Gemin2 (SIP1), Gemin3 and Gemin4 and in addition associates with PPP4c. The SMN complex has been implicated in the assembly and maturation of small nuclear ribonucleoproteins (snRNPs). Expression of GFP-R2-PPP4c in HeLa cells enhances the temporal localisation of newly formed snRNPs, which is consistent with an association of R2-PPP4c with the SMN protein complex.
authors.affiliation: Medical Research Council Protein Phosphorylation Unit, Division of Cell Signalling, University of Dundee, Dundee DD1 5EH, Scotland, UK.
authors.forename: Graeme K
authors.initials: GK
authors.lastname: Carnegie
authors.forename: Judith E
authors.initials: JE
authors.lastname: Sleeman
authors.forename: Nick
authors.initials: N
authors.lastname: Morrice
authors.forename: C James
authors.initials: CJ
authors.lastname: Hastie
authors.forename: Mark W
authors.initials: MW
authors.lastname: Peggie
authors.forename: Amanda
authors.initials: A
authors.lastname: Philp
authors.forename: Angus I
authors.initials: AI
authors.lastname: Lamond
authors.forename: Patricia T W
authors.initials: PT
authors.lastname: Cohen
mesh_terms: D015152:Blotting, Northern; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002893:Chromosomes, Human, Pair 3 / Q000648:ultrastructure; D002895:Chromosomes, Human, Pair 5 / Q000648:ultrastructure; D020541:Coiled Bodies / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein; D055541:DEAD Box Protein 20; D053487:DEAD-box RNA Helicases; D018076:DNA, Complementary / Q000378:metabolism; D019281:Dimerization; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes; D006367:HeLa Cells; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008856:Microscopy, Fluorescence; D015778:Minor Histocompatibility Antigens; D009134:Muscular Atrophy, Spinal / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009687:Nuclear Proteins / Q000096:biosynthesis; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012313:RNA / Q000378:metabolism; D020365:RNA Helicases / Q000096:biosynthesis; D016601:RNA-Binding Proteins; D017411:Ribonucleoproteins, Small Nuclear / Q000378:metabolism*; D055532:SMN Complex Proteins; D013997:Time Factors; D014018:Tissue Distribution; D014162:Transfection
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D018076:DNA, Complementary; D000939:Epitopes; C406815:GEMIN4 protein, human; D015778:Minor Histocompatibility Antigens; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; D017411:Ribonucleoproteins, Small Nuclear; D055532:SMN Complex Proteins; D012313:RNA; D010749:Phosphoprotein Phosphatases; C080406:protein phosphatase 4; C120168:DDX20 protein, human; D055541:DEAD Box Protein 20; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases