PNUTS forms a trimeric protein complex with GABA(C) receptors and protein phosphatase 1.
Phosphorylation and dephosphorylation of neurotransmitter receptors represent an important mechanism to regulate synaptic signal transduction. Here, we identified PNUTS, a targeting subunit of protein phosphatase 1 (PP1) as a new binding partner of GABA(C) receptors. In the mammalian retina, PNUTS is co-expressed with GABA(C) receptors and PP1 in bipolar cells. PNUTS and PP1 were detected in membrane protein preparations of the retina and precipitate with GABA(C) receptor specific antibodies. Furthermore, PNUTS shuttles from the nucleus to the membrane in cells co-expressing GABA(C) receptors. We show simultaneous binding of PP1 and GABA(C) receptors to different domains of PNUTS, demonstrating that PNUTS cross-links PP1 and GABA(C) receptors. Finally, modeling studies showed that the PP1 docking motif of PNUTS fits into the binding pocket on the enzyme surface, despite a C-terminal adjacent proline. We suggest that PNUTS targets PP1 to synaptic sites, acting as a temporary bridge between the phosphatase and GABA(C) receptors.
Rose
Melanie
M
Institut für Biochemie (Emil-Fischer-Zentrum), Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
Dütting
Eva
E
Schröder
Nadja
N
Sticht
Heinrich
H
Brandstätter
Johann Helmut
JH
Enz
Ralf
R
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D009687:Nuclear Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D054645:Protein Phosphatase 1 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D018079:Receptors, GABA / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
D004268:DNA-Binding Proteins; C087200:GABA-C receptor; D046912:Multiprotein Complexes; D009687:Nuclear Proteins; C110225:PPP1R10 protein, human; D016601:RNA-Binding Proteins; D018079:Receptors, GABA; D054645:Protein Phosphatase 1