Imaging the cell surface and its organization down to the level of single molecules
Klenerman D, Shevchuk A, Novak P, Korchev YE, Davis SJ (2012), Philos Trans R Soc Lond B Biol Sci. 368, 20120027
Determining the organization of key molecules on the surface of live cells in two dimensions and how this changes during biological processes, such as signalling, is a major challenge in cell biology and requires methods with nanoscale spatial resolution and high temporal resolution. Here, we review biophysical tools, based on scanning ion conductance microscopy and single-molecule fluorescence and the combination of both of these methods, which have recently been developed to address these issues. We then give examples of how these methods have been be applied to provide new insights into cell membrane organization and function, and discuss some of the issues that will need to be addressed to further exploit these methods in the future.
Key figure: TCCD analysis of a resting T cell
(a) All the components of the triggering apparatus of a T cell, i.e. MHC-peptide (HLA-DR), CD4 and CD45, give the same low value of association quotient (Q), a measure of the fraction of associated molecules, as the positive control monomeric protein, CD2. The dimer control, CD3, gives much higher levels of coincidence (each T-cell receptor contains two CD3 (epsilon) signalling subunits). The data are from James et al. . (b) Cartoon of some of the likely stoichiometries of the triggering apparatus of the T cell, based on the TCCD experiments.