title: Rapsyn mediates subsynaptic anchoring of PKA type I and stabilisation of acetylcholine receptor in vivo.
abstract: The stabilisation of acetylcholine receptors (AChRs) at the neuromuscular junction depends on muscle activity and the cooperative action of myosin Va and protein kinase A (PKA) type I. To execute its function, PKA has to be present in a subsynaptic microdomain where it is enriched by anchoring proteins. Here, we show that the AChR-associated protein, rapsyn, interacts with PKA type I in C2C12 and T-REx293 cells as well as in live mouse muscle beneath the neuromuscular junction. Molecular modelling, immunoprecipitation and bimolecular fluorescence complementation approaches identify an α-helical stretch of rapsyn to be crucial for binding to the dimerisation and docking domain of PKA type I. When expressed in live mouse muscle, a peptide encompassing the rapsyn α-helical sequence efficiently delocalises PKA type I from the neuromuscular junction. The same peptide, as well as a rapsyn construct lacking the α-helical domain, induces severe alteration of acetylcholine receptor turnover as well as fragmentation of synapses. This shows that rapsyn anchors PKA type I in close proximity to the postsynaptic membrane and suggests that this function is essential for synapse maintenance.
authors.affiliation: Institut für Toxikologie und Genetik, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen,  Germany.
authors.forename: Kyeong-Rok
authors.initials: KR
authors.lastname: Choi
authors.forename: Marco
authors.initials: M
authors.lastname: Berrera
authors.forename: Markus
authors.initials: M
authors.lastname: Reischl
authors.forename: Siegfried
authors.initials: S
authors.lastname: Strack
authors.forename: Marina
authors.initials: M
authors.lastname: Albrizio
authors.forename: Ira V
authors.initials: IV
authors.lastname: Röder
authors.forename: Anika
authors.initials: A
authors.lastname: Wagner
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Petersen
authors.forename: Mathias
authors.initials: M
authors.lastname: Hafner
authors.forename: Manuela
authors.initials: M
authors.lastname: Zaccolo
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Rudolf
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D054743:Cyclic AMP-Dependent Protein Kinase Type I / Q000737:chemistry / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000294:innervation / Q000378:metabolism; D009469:Neuromuscular Junction / Q000378:metabolism; D054730:Protein Interaction Domains and Motifs; D055550:Protein Stability; D017433:Protein Structure, Secondary; D011950:Receptors, Cholinergic / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013569:Synapses / Q000378:metabolism*
chemical_list: D009124:Muscle Proteins; D011950:Receptors, Cholinergic; C051609:peripheral membrane protein 43K; D054743:Cyclic AMP-Dependent Protein Kinase Type I