nn5b07595_si_001.pdf (10.06 MB)
Glasslike Membrane Protein Diffusion in a Crowded Membrane
journal contribution
posted on 2016-02-09, 00:00 authored by Ignacio Munguira, Ignacio Casuso, Hirohide Takahashi, Felix Rico, Atsushi Miyagi, Mohamed Chami, Simon ScheuringMany
functions of the plasma membrane depend critically on its
structure and dynamics. Observation of anomalous diffusion in vivo and in vitro using fluorescence
microscopy and single particle tracking has advanced our concept of the membrane from a homogeneous
fluid bilayer with freely diffusing proteins to a highly organized
crowded and clustered mosaic of lipids and proteins. Unfortunately,
anomalous diffusion could not be related to local molecular details
given the lack of direct and unlabeled molecular observation capabilities.
Here, we use high-speed atomic force microscopy and a novel analysis
methodology to analyze the pore forming protein lysenin in a highly
crowded environment and document coexistence of several diffusion
regimes within one membrane. We show the formation of local glassy
phases, where proteins are trapped in neighbor-formed cages for time
scales up to 10 s, which had not been previously experimentally reported
for biological membranes. Furthermore, around solid-like patches and
immobile molecules a slower glass phase is detected leading to protein
trapping and creating a perimeter of decreased membrane diffusion.