title: Cyclic inhibition-potentiation of the crosslinking of synapsin I with brain microtubules by protein kinase FA (an activator of ATP.Mg-dependent protein phosphatase).
abstract: The ATP.Mg-dependent type-1 protein phosphatase activating factor (FA) was identified as a protein kinase that could phosphorylate synapsin I, a neuronal protein that coats synaptic vesicles, binds to cytoskeleton and is believed to be involved in the modulation of neurotransmission. More importantly, more than 90% of the phosphates in 32P-synapsin I phosphorylated by FA could be removed by the activated ATP.Mg-dependent type-1 protein phosphatase and the synapsin I phosphatase activity was found to be strictly FA-dependent. Functional study further revealed that as a synapsin I kinase, factor FA could phosphorylate synapsin I and thereby inhibits crosslinking of synapsin I with tubulin, while as a synapsin I phosphatase activator, FA could promote the crosslinking copolymerization of synapsin I with tubulin. Taken together, the results provide initial evidence that a cyclic modulation of the crosslinking copolymerization of synapsin I with brain microtubules can be controlled by factor FA, representing an efficient cyclic cascade control mechanism for the regulation of axonal transport process during neurotransmission.
authors.affiliation: Institute of Biomedical and Life Sciences, National Tsing Hua University, Taiwan, ROC.
authors.forename: S D
authors.initials: SD
authors.lastname: Yang
authors.forename: J S
authors.initials: JS
authors.lastname: Song
authors.forename: Y T
authors.initials: YT
authors.lastname: Hsieh
authors.forename: W H
authors.initials: WH
authors.lastname: Chan
authors.forename: H W
authors.initials: HW
authors.lastname: Liu
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D003432:Cross-Linking Reagents; D007700:Kinetics; D008870:Microtubules / Q000378:metabolism*; D008970:Molecular Weight; D010764:Phosphorylase Kinase / Q000378:metabolism; D010762:Phosphorylase a / Q000378:metabolism; D010763:Phosphorylase b / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D013552:Swine; D016704:Synapsins / Q000302:isolation & purification / Q000378:metabolism*; D013572:Synaptic Vesicles / Q000378:metabolism; D014404:Tubulin / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D003432:Cross-Linking Reagents; D016704:Synapsins; D014404:Tubulin; D010762:Phosphorylase a; D010763:Phosphorylase b; D011494:Protein Kinases; D010764:Phosphorylase Kinase; D017871:Calcium-Calmodulin-Dependent Protein Kinases