title: Fluorescence correlation spectroscopy analysis of the hydrophobic interactions of protein 4.1 with phosphatidyl serine liposomes.
abstract: Fluorescence correlation spectroscopy (FCS) was applied to examine the interactions between a protein and a membrane lipid. The protein 4.1-phosphatidyl serine (PS) interactions served as the model system to demonstrate the membrane lipid-protein interactions. This protein was labeled with rhodamine and its interactions with PS-liposomes were measured by FCS. The present results clearly demonstrated that a small protein molecule, protein 4.1, interacts specifically with a large particle, a PS-liposome. This interaction appears to be hydrophobic and not electrostatic, since the bound protein 4.1 did not dissociate in solution and was specifically released from PS-liposomes by treatment with phospholipase A(2) (PLA(2)). In the present study, using FCS we could demonstrate that the serine residue of PS is required for protein 4.1 to bind to PS-liposomes and that the bound protein 4.1 is closely associated with the fatty acid of the PS molecule in the liposomes.
authors.affiliation: Department of Biochemistry, Tokyo Women's Medical University, School of Medicine, 8-1 Kawada-cho, Shinjyuku, 162-8666 Tokyo, Japan. takakuwa@research.twmu.ac.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Takakuwa
authors.forename: C G
authors.initials: CG
authors.lastname: Pack
authors.forename: X L
authors.initials: XL
authors.lastname: An
authors.forename: S
authors.initials: S
authors.lastname: Manno
authors.forename: E
authors.initials: E
authors.lastname: Ito
authors.forename: M
authors.initials: M
authors.lastname: Kinjo