A giant liposome for single-molecule observation of conformational changes in membrane proteins

Yasuhiro Onoue, Toshiharu Suzuki, Max Davidson, Mattias Karlsson, Owe Orwar, Masasuke Yoshida, Kazuhiko Kinosita*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    9 Citations (Scopus)


    We present an experimental system that allows visualization of conformational changes in membrane proteins at the single-molecule level. The target membrane protein is reconstituted in a giant liposome for independent control of the aqueous environments on the two sides of the membrane. For direct observation of conformational changes, an extra-liposomal site(s) of the target protein is bound to a glass surface, and a probe that is easily visible under a microscope, such as a micron-sized plastic bead, is attached to another site on the intra-liposomal side. A conformational change, or an angular motion in the tiny protein molecule, would manifest as a visible motion of the probe. The attachment of the protein on the glass surface also immobilizes the liposome, greatly facilitating its manipulation such as the probe injection. As a model system, we reconstituted ATP synthase (FOF1) in liposomes tens of μm in size, attached the protein specifically to a glass surface, and demonstrated its ATP-driven rotation in the membrane through the motion of a submicron bead.

    Original languageEnglish
    Pages (from-to)1332-1340
    Number of pages9
    JournalBiochimica et Biophysica Acta - Biomembranes
    Issue number6
    Publication statusPublished - 2009 Jun


    • ATP synthase
    • Conformational change
    • Giant liposome
    • Membrane protein
    • Single-molecule

    ASJC Scopus subject areas

    • Biochemistry
    • Cell Biology
    • Biophysics


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