title: Membrane switch hypothesis. 1. Cell density influences lateral domain structure of tumor cell membranes.
abstract: The domain structure of human cancer cells membranes was investigated by electron paramagnetic resonance (EPR) in different phases of cell growth, and the results were compared to those obtained for nonmalignant cells. On the basis of computer simulation of the EPR spectra using a newly developed GHOST condensation routine it was suggested that plasma membranes of cancer cells have less lateral lipid domain types at confluent conditions than in the exponential growing phase, while in nonmalignant cells the domain structure does not change significantly during cell growth. In accordance to our experimental data we propose a membrane switch hypothesis: disappearance of certain membrane domain types might act as a switch promoting the clustering of membrane constituents into the active units in a common lipid membrane domain and thus influencing the physiology of cells.
authors.affiliation: EPR Center, "JoZef Stefan" Institute, Jamova 39, 1001 Ljubljana, Slovenia. tilen.koklic@ijs.si
authors.forename: Tilen
authors.initials: T
authors.lastname: Koklic
authors.forename: Mateja
authors.initials: M
authors.lastname: Pirs
authors.forename: Reiner
authors.initials: R
authors.lastname: Zeisig
authors.forename: Zrinka
authors.initials: Z
authors.lastname: Abramović
authors.forename: Marjeta
authors.initials: M
authors.lastname: Sentjurc
mesh_terms: D002452:Cell Count; D002460:Cell Line; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000737:chemistry* / Q000502:physiology*; D003198:Computer Simulation; D004578:Electron Spin Resonance Spectroscopy; D006801:Humans; D008560:Membrane Fluidity; D008565:Membrane Proteins / Q000378:metabolism; D009369:Neoplasms / Q000737:chemistry* / Q000648:ultrastructure*
chemical_list: D008565:Membrane Proteins