title: Channel-forming activities of peroxisomal membrane proteins from the yeast Saccharomyces cerevisiae.
abstract: Highly-purified peroxisomes from the yeast Saccharomyces cerevisiae grown on oleic acid were investigated for the presence of channel (pore)-forming proteins in the membrane of these organelles. Solubilized membrane proteins were reconstituted in planar lipid bilayers and their pore-forming activity was studied by means of multiple-channel monitoring or single-channel analysis. Two abundant pore-forming activities were detected with an average conductance of 0.2 and 0.6 nS in 1.0 m KCl, respectively. The high-conductance pore (0.6 nS in 1.0 m KCl) is slightly selective to cations (P(K+)/P(Cl-) approximately 1.3) and showed an unusual flickering at elevated (> +/-40 mV) holding potentials directed upward relative to the open state of the channel. The data obtained for the properties of the low-conductance pore (0.2 nS in 1.0 m KCl) support the notion that the high-conductance channel represents a cluster of two low-conductance pores. The results lead to conclusion that the yeast peroxisomes contain membrane pore-forming proteins that may aid the transfer of small solutes between the peroxisomal lumen and cytoplasm.
authors.affiliation: Institut für Physiologische Chemie, Abt. Systembiochemie, Bochum, Germany.
authors.forename: Silke
authors.initials: S
authors.lastname: Grunau
authors.forename: Sabrina
authors.initials: S
authors.lastname: Mindthoff
authors.forename: Hanspeter
authors.initials: H
authors.lastname: Rottensteiner
authors.forename: Raija T
authors.initials: RT
authors.lastname: Sormunen
authors.forename: J Kalervo
authors.initials: JK
authors.lastname: Hiltunen
authors.forename: Ralf
authors.initials: R
authors.lastname: Erdmann
authors.forename: Vasily D
authors.initials: VD
authors.lastname: Antonenkov
mesh_terms: D004591:Electrophoresis, Polyacrylamide Gel; D007473:Ion Channels / Q000378:metabolism*; D008051:Lipid Bilayers; D046529:Microscopy, Electron, Transmission; D020675:Peroxisomes / Q000201:enzymology / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
chemical_list: D007473:Ion Channels; D008051:Lipid Bilayers; D029701:Saccharomyces cerevisiae Proteins