title: Phactr3/scapinin, a member of protein phosphatase 1 and actin regulator (phactr) family, interacts with the plasma membrane via basic and hydrophobic residues in the N-terminus.
abstract: Proteins that belong to the protein phosphatase 1 and actin regulator (phactr) family are involved in cell motility and morphogenesis. However, the mechanisms that regulate the actin cytoskeleton are poorly understood. We have previously shown that phactr3, also known as scapinin, localizes to the plasma membrane, including lamellipodia and membrane ruffles. In the present study, experiments using deletion and point mutants showed that the basic and hydrophobic residues in the N-terminus play crucial roles in the localization to the plasma membrane. A BH analysis (http://helixweb.nih.gov/bhsearch) is a program developed to identify membrane-binding domains that comprise basic and hydrophobic residues in membrane proteins. We applied this program to phactr3. The results of the BH plot analysis agreed with the experimentally determined region that is responsible for the localization of phactr3 to the plasma membrane. In vitro experiments showed that the N-terminal itself binds to liposomes and acidic phospholipids. In addition, we showed that the interaction with the plasma membrane via the N-terminal membrane-binding sequence is required for phactr3-induced morphological changes in Cos7 cells. The membrane-binding sequence in the N-terminus is highly conserved in all members of the phactr family. Our findings may provide a molecular basis for understanding the mechanisms that allow phactr proteins to regulate cell morphogenesis.
authors.affiliation: Department of Biomedical Laboratory Sciences, Health Sciences, Shinshu University, Matsumoto, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Itoh
authors.affiliation: Department of Biomedical Laboratory Sciences, Health Sciences, Shinshu University, Matsumoto, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Uchiyama
authors.affiliation: Department of Molecular Oncology, Medical Sciences, Shinshu University Graduate School of Medicine, Matsumoto, Japan.
authors.forename: Shunichiro
authors.initials: S
authors.lastname: Taniguchi
authors.affiliation: Department of Biomedical Laboratory Sciences, Health Sciences, Shinshu University, Matsumoto, Japan.
authors.forename: Junji
authors.initials: J
authors.lastname: Sagara
mesh_terms: D000818:Animals; D019556:COS Cells; D002462:Cell Membrane / Q000378:metabolism*; D002522:Chlorocebus aethiops; D017931:DNA Primers / Q000235:genetics; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D009154:Mutation / Q000235:genetics; D009687:Nuclear Proteins / Q000378:metabolism*; D011485:Protein Binding
chemical_list: D017931:DNA Primers; D009687:Nuclear Proteins; C479826:PHACTR3 protein, human; D049452:Green Fluorescent Proteins