Regulation of exocytosis through Ca2+/ATP-dependent binding of autophosphorylated Ca2+/calmodulin-activated protein kinase II to syntaxin 1A.
Syntaxin 1A/HPC-1 is a key component of the exocytotic molecular machinery, namely, the soluble N-ethylmaleimide-sensitive factor attachment protein (SNAP) receptor mechanism. Although >10 syntaxin-binding proteins have been identified, they cannot completely explain the regulation of exocytosis. Thus, novel proteins may interact with syntaxin. Because exocytosis requires both Ca2+ and ATP, we searched for Ca2+/ATP-dependent syntaxin-binding proteins from the rat brain and discovered Ca2+/calmodulin-activated protein kinase II (CaMKII)-alpha. At Ca2+ concentrations of >10(-6) m, only autophosphorylated CaMKII bound to syntaxin. Bound CaMKII was released from syntaxin by EGTA or by phosphatase, indicating that the binding is reversible. CaMKII bound to the linker domain of syntaxin, unlike any other known syntaxin-binding proteins. CaMKII-syntaxin complexes were also detected in synaptosomes by immunoprecipitation, and when reconstituted in vitro, they recruited larger amounts of synaptotagmin and SNAP-25 than syntaxin alone. The microinjected CaMKII-binding domain of syntaxin specifically affected exocytosis in chromaffin cells and in neurons. These results indicate that the Ca2+/ATP-dependent binding of CaMKII to syntaxin is an important process in the regulation of exocytosis.
Ohyama
Akihiro
A
Department of Molecular and Cellular Neurobiology, Gunma University School of Medicine, Maebashi, Gunma 371-8511, Japan.
Hosaka
Kohei
K
Komiya
Yoshiaki
Y
Akagawa
Kimio
K
Yamauchi
Emiko
E
Taniguchi
Hisaaki
H
Sasagawa
Nobuyuki
N
Kumakura
Konosuke
K
Mochida
Sumiko
S
Yamauchi
Takashi
T
Igarashi
Michihiro
M
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000954:Antigens, Surface / Q000737:chemistry / Q000378:metabolism*; D001923:Brain Chemistry; D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000737:chemistry / Q000378:metabolism*; D002384:Catalysis; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D019439:Chromaffin Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology*; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism; D051938:Munc18 Proteins; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010446:Peptide Fragments / Q000494:pharmacology; D010744:Phosphoric Monoester Hydrolases / Q000494:pharmacology; D010766:Phosphorylation; D017729:Presynaptic Terminals / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D051381:Rats; D050600:SNARE Proteins; D017783:Superior Cervical Ganglion; D050825:Synaptosomal-Associated Protein 25; D013574:Synaptosomes / Q000737:chemistry / Q000378:metabolism; D050857:Synaptotagmins; D050827:Syntaxin 1; D033921:Vesicular Transport Proteins
D000954:Antigens, Surface; D002135:Calcium-Binding Proteins; D002614:Chelating Agents; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D051938:Munc18 Proteins; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D050600:SNARE Proteins; C494210:Snap25 protein, rat; C494213:Stx1a protein, rat; D050825:Synaptosomal-Associated Protein 25; D050827:Syntaxin 1; D033921:Vesicular Transport Proteins; D050857:Synaptotagmins; D000255:Adenosine Triphosphate; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D010744:Phosphoric Monoester Hydrolases; D002118:Calcium