title: Transient GPI-anchored protein homodimers are units for raft organization and function.
abstract: Advanced single-molecule fluorescent imaging was applied to study the dynamic organization of raft-associated glycosylphosphatidylinositol-anchored proteins (GPI-APs) in the plasma membrane and their stimulation-induced changes. In resting cells, virtually all of the GPI-APs are mobile and continually form transient (~200 ms) homodimers (termed homodimer rafts) through ectodomain protein interactions, stabilized by the presence of the GPI-anchoring chain and cholesterol. Heterodimers do not form, suggesting a fundamental role for the specific ectodomain protein interaction. Under higher physiological expression conditions , homodimers coalesce to form hetero- and homo-GPI-AP oligomer rafts through raft-based lipid interactions. When CD59 was ligated, it formed stable oligomer rafts containing up to four CD59 molecules, which triggered intracellular Ca(2+) responses that were dependent on GPI anchorage and cholesterol, suggesting a key part played by transient homodimer rafts. Transient homodimer rafts are most likely one of the basic units for the organization and function of raft domains containing GPI-APs.
authors: Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto, Japan.
authors: Kenichi G N
authors: KG
authors: Suzuki
authors: Rinshi S
authors: RS
authors: Kasai
authors: Koichiro M
authors: KM
authors: Hirosawa
authors: Yuri L
authors: YL
authors: Nemoto
authors: Munenori
authors: M
authors: Ishibashi
authors: Yoshihiro
authors: Y
authors: Miwa
authors: Takahiro K
authors: TK
authors: Fujiwara
authors: Akihiro
authors: A
authors: Kusumi
mesh_terms: D018957:CD59 Antigens / Q000378:metabolism; D019281:Dimerization; D031541:Fluorescence Resonance Energy Transfer; D017261:Glycosylphosphatidylinositols / Q000378:metabolism*; D021962:Membrane Microdomains
chemical_list: D018957:CD59 Antigens; D017261:Glycosylphosphatidylinositols