Dynamics and size of cross-linking-induced lipid Nanodomains in model Membranes
2012 (English)In: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 102, no 9, 2104-2113 p.Article in journal (Refereed) Published
Changes of membrane organization upon cross-linking of its components trigger cell signaling response to various exogenous factors. Cross-linking of raft gangliosides GM1 with cholera toxin ( CTxB) was shown to cause microscopic phase separation in model membranes, and the CTxB-GM1 complexes forming a minimal lipid raft unit are the subject of ongoing cell membrane research. Yet, those subdiffraction sized rafts have never been described in terms of size and dynamics. By means of two-color z-scan fluorescence correlation spectroscopy, we show that the nanosized domains are formed in model membranes at lower sphingomyelin (Sph) content than needed for the large-scale phase separation and that the CTxB-GM1 complexes are confined in the domains poorly stabilized with Sph. Forster resonance energy transfer together with Monte Carlo modeling of the donor decay response reveal the domain radius of similar to 8 nm, which increases at higher Sph content. We observed two types of domains behaving differently, which suggests a dual role of the cross-linker: first, local transient condensation of the GM1 molecules compensating for a lack of Sph and second, coalescence of existing nanodomains ending in large-scale phase separation.
Place, publisher, year, edition, pages
2012. Vol. 102, no 9, 2104-2113 p.
IdentifiersURN: urn:nbn:se:umu:diva-56217DOI: 10.1016/j.bpj.2012.03.054ISI: 000303547700012OAI: oai:DiVA.org:umu-56217DiVA: diva2:532965