title: Tritium labelling of a cholesterol amphiphile designed for cell membrane anchoring of proteins.
abstract: Cell membrane association of proteins can be achieved by the addition of lipid moieties to the polypeptide chain, and such lipid-modified proteins have important biological functions. A class of cell surface proteins contains a complex glycosylphosphatidylinositol (GPI) glycolipid at the C-terminus, and they are accumulated in cholesterol-rich membrane microdomains, that is, lipid rafts. Semisynthetic lipoproteins prepared from recombinant proteins and designed lipids are valuable probes and model systems of the membrane-associated proteins. Because GPI-anchored proteins can be reinserted into the cell membrane with the retention of the biological function, they are appropriate candidates for preparing models via reduction of the structural complexity. A synthetic headgroup was added to the 3β-hydroxyl group of cholesterol, an essential lipid component of rafts, and the resulting cholesterol derivative was used as a simplified GPI mimetic. In order to quantitate the membrane integrated GPI mimetic after the exogenous addition to live cells, a tritium labelled cholesterol anchor was prepared. The radioactive label was introduced into the headgroup, and the radiolabelled GPI mimetic anchor was obtained with a specific activity of 1.37 TBq/mmol. The headgroup labelled cholesterol derivative was applied to demonstrate the sensitive detection of the cell membrane association of the anchor under in vivo conditions.
authors.affiliation: Laboratory of Chemical Biology, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Temesvári krt. 62., 6726, Szeged, Hungary.
authors.forename: Balázs
authors.initials: B
authors.lastname: Schäfer
authors.forename: Erika
authors.initials: E
authors.lastname: Orbán
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Kele
authors.forename: Csaba
authors.initials: C
authors.lastname: Tömböly
mesh_terms: D002784:Cholesterol / Q000031:analogs & derivatives* / Q000737:chemistry; D017261:Glycosylphosphatidylinositols / Q000138:chemical synthesis*; D013501:Surface-Active Agents / Q000138:chemical synthesis*; D014316:Tritium / Q000737:chemistry*
chemical_list: D017261:Glycosylphosphatidylinositols; D013501:Surface-Active Agents; D014316:Tritium; D002784:Cholesterol
keywords: cholesterol; lipoprotein; membrane anchor; tritium