title: Tubular membrane formation of binary giant unilamellar vesicles composed of cylinder and inverse-cone-shaped lipids.
abstract: We have succeeded in controlling tubular membrane formations in binary giant unilamellar vesicles (GUVs) using a simple temperature changing between the homogeneous one-phase region and the two-phase coexistence region. The binary GUV is composed of inverse-cone (bulky hydrocarbon chains and a small headgroup) and cylinder-shaped lipids. When the temperature was set in the two-phase coexistence region, the binary GUV had a spherical shape with solidlike domains. By increasing the temperature to the homogeneous one-phase region, the excess area created by the chain melting of the lipid produced tubes inside the GUV. The tubes had a radius on the micrometer scale and were stable in the one-phase region. When we again decreased the temperature to the two-phase coexisting region, the tubes regressed and the GUVs recovered their phase-separated spherical shape. We infer that the tubular formation was based on the mechanical balance of the vesicle membrane (spontaneous tension) coupled with the asymmetric distribution of the inverse-cone-shaped lipids between the inner and outer leaflets of the vesicle (lipid sorting).
authors.affiliation: Department of Physics, Tohoku University, Aoba, Sendai, Japan. Electronic address: sakuma@bio.phys.tohoku.ac.jp.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Sakuma
authors.forename: Takashi
authors.initials: T
authors.lastname: Taniguchi
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Kawakatsu
authors.forename: Masayuki
authors.initials: M
authors.lastname: Imai
mesh_terms: D001696:Biomechanical Phenomena; D002462:Cell Membrane / Q000737:chemistry*; D008958:Models, Molecular; D010743:Phospholipids / Q000737:chemistry*; D053835:Unilamellar Liposomes / Q000737:chemistry*
chemical_list: D010743:Phospholipids; D053835:Unilamellar Liposomes