Phosphorylation of adult type Sept5 (CDCrel-1) by cyclin-dependent kinase 5 inhibits interaction with syntaxin-1.
Increasing evidence implicates cyclin-dependent kinase 5 (Cdk5) in neuronal synaptic function. We searched for Cdk5 substrates in synaptosomal fractions prepared from mouse brains. Mass spectrometric analysis after two-dimensional SDS-PAGE identified several synaptic proteins phosphorylated by Cdk5-p35; one protein identified was Sept5 (CDCrel-1). Although septins were isolated originally as cell division-related proteins in yeast, Sept5 is expressed predominantly in neurons and is implicated in exocytosis. We confirmed that Sept5 is phosphorylated by Cdk5-p35 in vitro and identified Ser17 of adult type Sept5 (Sept5_v1) as a major phosphorylation site. We found that Ser17 of Sept5_v1 is phosphorylated in mouse brains. Coimmunoprecipitation from synaptosomal fractions and glutathione S-transferase-syntaxin-1A pulldown assays of Sept5_v1 expressed in COS-7 cells showed that phosphorylation of Sept5_v1 by Cdk5-p35 decreases the binding to syntaxin-1. These results indicate that the interaction of Sept5 with syntaxin-1 is regulated by the phosphorylation of Sept5_v1 at Ser17 by Cdk5-p35.
Taniguchi
Makoto
M
Department of Biological Sciences, Graduate School of Science, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan. taniguti-makoto@c.metro-u.ac.jp
Taoka
Masato
M
Itakura
Makoto
M
Asada
Akiko
A
Saito
Taro
T
Kinoshita
Makoto
M
Takahashi
Masami
M
Isobe
Toshiaki
T
Hisanaga
Shin-ichi
S
D000818:Animals; D001921:Brain / Q000378:metabolism; D019556:COS Cells; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002522:Chlorocebus aethiops; D051360:Cyclin-Dependent Kinase 5 / Q000378:metabolism*; D013058:Mass Spectrometry; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D058112:Septins; D013347:Subcellular Fractions / Q000378:metabolism; D013569:Synapses / Q000378:metabolism; D013574:Synaptosomes / Q000378:metabolism; D050827:Syntaxin 1 / Q000378:metabolism*
D018797:Cell Cycle Proteins; D050827:Syntaxin 1; D051360:Cyclin-Dependent Kinase 5; C491612:Sept5 protein, mouse; D058112:Septins