title: Ultrafine membrane compartments for molecular diffusion as revealed by single molecule techniques.
abstract: Plasma membrane compartments, delimited by transmembrane proteins anchored to the membrane skeleton (anchored-protein picket model), would provide the membrane with fundamental mosaicism because they would affect the movement of practically all molecules incorporated in the cell membrane. Understanding such basic compartmentalized structures of the cell membrane is critical for further studies of a variety of membrane functions. Here, using both high temporal-resolution single particle tracking and single fluorescent molecule video imaging of an unsaturated phospholipid, DOPE, we found that plasma membrane compartments generally exist in various cell types, including CHO, HEPA-OVA, PtK2, FRSK, HEK293, HeLa, T24 (ECV304), and NRK cells. The compartment size varies from 30 to 230 nm, whereas the average hop rate of DOPE crossing the boundaries between two adjacent compartments ranges between 1 and 17 ms. The probability of passing a compartment barrier when DOPE is already at the boundary is also cell-type dependent, with an overall variation by a factor of approximately 7. These results strongly indicate the necessity for the paradigm shift of the concept on the plasma membrane: from the two-dimensional fluid continuum model to the compartmentalized membrane model in which its constituent molecules undergo hop diffusion over the compartments.
authors.affiliation: Kusumi Membrane Organizer Project, Exploratory Research for Advanced Technology Organization (ERATO/SORST), Japan Science and Technology Agency, Nagoya, Japan.
authors.forename: Kotono
authors.initials: K
authors.lastname: Murase
authors.forename: Takahiro
authors.initials: T
authors.lastname: Fujiwara
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Umemura
authors.forename: Kenichi
authors.initials: K
authors.lastname: Suzuki
authors.forename: Ryota
authors.initials: R
authors.lastname: Iino
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Yamashita
authors.forename: Mihoko
authors.initials: M
authors.lastname: Saito
authors.forename: Hideji
authors.initials: H
authors.lastname: Murakoshi
authors.forename: Ken
authors.initials: K
authors.lastname: Ritchie
authors.forename: Akihiro
authors.initials: A
authors.lastname: Kusumi
mesh_terms: D000818:Animals; D016466:CHO Cells; D002451:Cell Compartmentation / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D002784:Cholesterol / Q000737:chemistry; D006224:Cricetinae; D003412:Cricetulus; D003599:Cytoskeleton / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism; D005456:Fluorescent Dyes / Q000737:chemistry; D006367:HeLa Cells; D006801:Humans; D008962:Models, Theoretical; D010714:Phosphatidylethanolamines / Q000737:chemistry*; D051381:Rats
chemical_list: C410262:1,2-dioleoyl-glycero-3-phosphatidyl ethanolamine; D005456:Fluorescent Dyes; D010714:Phosphatidylethanolamines; D002784:Cholesterol