Clustering on Membranes: Fluctuations and More. Issue 5 (May 2018)

• Record Type: Journal Article
• Authors: Johannes, Ludger; Pezeshkian, Weria; Ipsen, John H.; Shillcock, Julian C.
• Is Part Of: Trends in cell biology. Volume 28:Issue 5(2018)
• Page Start: 405
• Page End: 415
• Publication Date: 2018-05
• Subjects: Cytology -- Periodicals; Cytology -- Research -- Periodicals; 571.6
• DOI: 10.1016/j.tcb.2018.01.009
• Languages: English
• ISSNs: 0962-8924

Abstract

Abstract : Clustering of extracellular ligands and proteins on the plasma membrane is required to perform specific cellular functions, such as signaling and endocytosis. Attractive forces that originate in perturbations of the membrane's physical properties contribute to this clustering, in addition to direct protein–protein interactions. However, these membrane-mediated forces have not all been equally considered, despite their importance. In this review, we describe how line tension, lipid depletion, and membrane curvature contribute to membrane-mediated clustering. Additional attractive forces that arise from protein-induced perturbation of a membrane's fluctuations are also described. This review aims to provide a survey of the current understanding of membrane-mediated clustering and how this supports precise biological functions. Highlights: Membrane-mediated clustering forces contribute to biological processes on cellular membranes, such as intracellular trafficking and signaling; they have their origin in a protein's ability to physically perturb the membrane's relaxed state. There are four categories of membrane-mediated clustering forces: capillary, lipid depletion, curvature, and fluctuation (or thermal Casimir-like). Thermal Casimir-like forces originate from the perturbation of any of the following degrees of freedom in the membrane fluctuation spectrum: peristaltic thickness fluctuations, local protrusion modes, lipid density fluctuations, and fluctuations of lipid tilt. Thermal Casimir-like forces are as strong as conventional subnanometric van der Waals, screened electrostatics, or hydrogen bonding forces; as opposed to these, thermal Casimir-like forces operate at nanometric (mesoscopic) length scales and are generic. To induce biologically relevant thermal Casimir-like forces, a nano-object (such as a protein or nanoparticle) must be rigid and adsorb tightly to an area of membrane at least a few nanometers in linear extent. Recent experimental evidence suggests that thermal Casimir-like forces contribute to the clustering of bacterial Shiga toxin molecules.