Abstract
Nano-domains are sub-light-diffraction-sized heterogeneous areas in the plasma membrane of cells, which are involved in cell signalling and membrane trafficking. Throughout the last thirty years, these nano-domains have been researched extensively and have been the subject of multiple theories and models: the lipid raft theory, the fence model, and the protein oligomerization theory. Strong evidence exists for all of these, and consequently they were combined into a hierarchal model. Measurements of protein and lipid diffusion coefficients and patterns have been instrumental in plasma membrane research and by extension in nano-domain research. This has led to the development of multiple methodologies that can measure diffusion and confinement parameters including single particle tracking, fluorescence correlation spectroscopy, image correlation spectroscopy and fluorescence recovery after photobleaching. Here we review the performance and strengths of these methods in the context of their use in identification and characterization of plasma membrane nano-domains.
Highlights
SDU Biotechnology, Department of Chemical Engineering, Biotechnology and Environmental Technology, DTU Health Tech, Department of Health Technology, Technical University of Denmark, Ørsteds Plads, Department of Chemistry, McGill University, 801 Sherbrooke St
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If the will be identified as a STALL diffusion type, if the intercept is significantly negative it correlates to hop intercept is significantly positive it will be identified as a STALL diffusion type, if the intercept is diffusion representative of actin derived nano-domains, and if the intercept is zero it is described as free significantly negative it correlates to hop diffusion representative of actin derived nano‐domains, and if the intercept is zero it is described as free diffusion
Summary
Since the development of the Fluid Mosaic Model [1], multiple new models have been proposed and sensitive methods developed to both explain and probe the heterogeneity of the plasma membrane. The hierarchal model was proposed to describe the plasma membrane [15], which included both the lipid nano-domains and the actin-derived nano-domains and a group that is defined as oligomerized membrane proteins. Membrane trafficking [19], nano-domains are implicated in various diseases like cancer [20] and cardiovascular diseases [21] Based on these essential functions of the nano-domains in plasma membrane, it is essential to have valid methods for their identification and characterization to understand their functions in greater detail. Over the time period that models of membrane nano-domains have been developed and refined, multiple analytical methodologies have been introduced to define them through measurements. Many different methodologies are used in current research of nano-domains, including the detergent method, model membranes, cholesterol manipulation, membrane sensitive probing and diffusion methods. The focus of this review will be to provide insight on the various methods to analyse nano-domains based on molecular diffusive behaviour and will include a discussion about their individual strengths and weaknesses
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