Interaction of the cellular prion protein with raft-like lipid membranes.
Conversion of the cellular isoform of the prion protein (PrP(C)) into the disease-associated isoform (PrP(Sc)) plays a key role in the development of prion diseases. Within its cellular pathway, PrP(C) undergoes several posttranslational modifications, i.e., the attachment of two N-linked glycans and a glycosyl phosphatidyl inositol (GPI) anchor, by which it is linked to the plasma membrane on the exterior cell surface. To study the interaction of PrP(C) with model membranes, we purified posttranslationally modified PrP(C) from transgenic Chinese hamster ovary (CHO) cells. The mono-, di- and oligomeric states of PrP(C) free in solution were analyzed by analytical ultracentrifugation. The interaction of PrP(C) with model membranes was studied using both lipid vesicles in solution and lipid bilayers bound to a chip surface. The equilibrium and mechanism of PrP(C) association with the model membranes were analyzed by surface plasmon resonance. Depending on the degree of saturation of binding sites, the concentration of PrP(C) released from the membrane into aqueous solution was estimated at between 10(-9) and 10(-7) M. This corresponds to a free energy of the insertion reaction of -48 kJ/mol. Consequences for the conversion of PrP(C) to PrP(Sc) are discussed.
Elfrink
Kerstin
K
Institut für Physikalische Biologie and Biologisch-Medizinisches Forschungszentrum, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany.
Nagel-Steger
Luitgard
L
Riesner
Detlev
D
D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D007700:Kinetics; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism; D021962:Membrane Microdomains / Q000737:chemistry / Q000378:metabolism*; D008954:Models, Biological; D018621:PrPC Proteins / Q000737:chemistry / Q000378:metabolism; D011328:Prions / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism; D020349:Surface Plasmon Resonance; D013997:Time Factors
D008051:Lipid Bilayers; D018621:PrPC Proteins; D011328:Prions; D020033:Protein Isoforms