Phosphorylation of the α Subunit of Rat Brain Sodium Channels by cAMP-dependent Protein Kinase at a New Site Containing Ser686 and Ser687

摘要: Abstract The alpha subunit of the rat brain sodium channel is phosphorylated by cAMP-dependent protein kinase in vitro and situ at multiple sites which yield seven tryptic phosphopeptides. Phosphopeptides 1-4 7 are derived from phosphorylation between residues 554 623 a single large CNBr fragment cytoplasmic segment connecting homologous domains I II (Rossie, S., Gordon, D., Catterall, W. A. (1987) J. Biol. Chem. 262, 17530-17535). In present work, antibodies were prepared against synthetic peptide corresponding to 676-692 (AbSP15), contain one additional potential site Ser686-Ser687 different predicted this same intracellular segment. AbSP15 recognizes native denatured channels specifically immunoprecipitates fragments low molecular mass that new kinase. Comparison phosphopeptides intact subunits with those isolated immunoprecipitation indicates two previously unidentified 5 6 arise containing Ser686-Ser687. These results identify show major channel, both neurons, all located cluster 687 II.