title: Inhibitory effect of NAP-22 on the phosphatase activity of synaptojanin-1.
abstract: Endocytosis of the synaptic vesicle is a complicated process, in which many proteins and lipids participate. Phosphatidylinositol 4,5-bisphosphate (PIP(2) ) plays important roles in the process, and the dynamic regulation of this lipid is one of the key events. Synaptojanin is a PIP(2) phosphatase, and dephosphorylation of PIP(2) of the clathrin coated-vesicle results in the uncoating of the vesicle. NAP-22 is one of the major proteins of the neuronal detergent-resistant membrane microdomain and localizes in both the presynaptic plasma membrane and the synaptic vesicle. To elucidate the role of NAP-22 in synaptic function, a screening of the NAP-22 binding proteins through pull-down assay was performed. In addition to CapZ protein, synaptojanin-1 was detected by LC-MS/MS, and Western blotting using antisynaptojanin-1 confirmed this result. The interaction seems to be important in the course of synaptic vesicle endocytosis, because NAP-22 inhibited the phosphatase activity of synaptojanin in a dose-dependent manner. The inhibitory region for 5-phosphatase and the binding region for PIP(2) overlapped in the amino acid sequence of NAP-22, so elucidation of the regulatory mechanism of the PIP(2) binding ability of NAP-22 could be important in understanding the membrane dynamics at the presynaptic region.
authors.affiliation: Department of Biology, Graduate School of Science, Kobe University, Kobe, Japan.
authors.forename: Rika
authors.initials: R
authors.lastname: Takaichi
authors.forename: Sin-Ichi
authors.initials: S
authors.lastname: Odagaki
authors.forename: Haruko
authors.initials: H
authors.lastname: Kumanogoh
authors.forename: Shun
authors.initials: S
authors.lastname: Nakamura
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Morita
authors.forename: Shohei
authors.initials: S
authors.lastname: Maekawa
mesh_terms: D000818:Animals; D001921:Brain / Q000648:ultrastructure; D002148:Calmodulin-Binding Proteins / Q000378:metabolism*; D051347:CapZ Actin Capping Protein / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D002461:Cell Line, Transformed; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D004705:Endocytosis; D006801:Humans; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013569:Synapses / Q000378:metabolism* / Q000648:ultrastructure; D013572:Synaptic Vesicles / Q000378:metabolism; D053719:Tandem Mass Spectrometry / Q000379:methods
chemical_list: D002148:Calmodulin-Binding Proteins; D051347:CapZ Actin Capping Protein; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D009419:Nerve Tissue Proteins; C066853:Basp1 protein, rat; C097702:synaptojanin; D010744:Phosphoric Monoester Hydrolases