Protein mediated membrane adhesion

Abstract

Adhesion in the context of mechanical attachment, signaling, and movement in cellular dynamics is mediated by the kinetic interactions between membrane-embedded proteins in an aqueous environment. Here, we present a minimal theoretical framework for the dynamics of membrane adhesion that accounts for the kinetics of protein binding, the elastic deformation of the membrane, and the hydrodynamics of squeeze flow in the membrane gap. We analyze the resulting equations using scaling estimates to characterize the spatiotemporal features of the adhesive patterning and corroborate them using numerical simulations. In addition to characterizing aspects of cellular dynamics, our results might also be applicable to a range of phenomena in physical chemistry and materials science where flow, deformation, and kinetics are coupled to each other in slender geometries.

Elastohydrodynamics and Kinetics of Protein Patterning in the Immunological Synapse

“…Alternatively, if we assume that the off-rate increases with spring tension, so that proteins would unbind as h ≪ l i and h ≫ l i and in its simplest form given by a constant off-rate ( σ off = ∞) in Eq 4 that produce similar results (see SI). Although the exact form of these rates are not known, experiments show that the the different protein pairs form non-overlapping patterns [ 2 , 3 , 20 ], which we mimic via the choice of the width of the kinetic distributions σ on = 0.2 and σ off = 0.6 [ 35 ]. Narrowing the distributions generates wider protein free areas that separate TCR-pMHC and LFA-ICAM rich regions.…”

“…At the edge of the IS the membrane is assumed to be torque free with no bending moment (∇ 2 h = 0) and at a constant pressure ( p = 0), which allows fluid flux through the boundary. The membrane is pinned at the edge ( h = 0.5 l 2 ) and the equilibrium number of proteins per membrane area at that given height ( C 1 = C 2 = 0.01 C 0 ) see [ 35 ] and S1 Text and S1 Fig for details. The membrane is initialized with six small Gaussian shaped bumps of different widths (≈ 0.1 L ) and amplitude ((0.075–0.1) l 2 ).…”

Peeling dynamics of fluid membranes bridged by molecular bonds: moving or breaking

“…For this reason, exploiting scale separation, we combine a vesicle-scale capillary model in terms of macroscopic quantities such as patch size, contact angle or vesicle pressure with a model for the micro-mechanics of the adhesion patch, taking the macroscopic quantities as parameters and resolving the force on bonds by accounting for the bending rigidity of the membrane κ and the compliance of the molecular bonds (figure 1 c , d ). In this model, the length scale over which the tension of the free-standing membrane is transmitted to the adhesion patch can be estimated by balancing the bending and the bond normal pressures as ℓ2=[4]κ/false(kc1false) [46], where k is the bond stiffness and c 1 is a typical bond concentration. Considering k = 2.5 × 10 −4 N m −1 and the values given above for κ and c 1 , we find that ℓ 2 ∼ 20 nm, much smaller than the typical size of an adhesion patch.…”

Universal self-similar attractor in the bending-driven levelling of thin viscous films

“…When subjected to a perturbation, this setting can exhibit a wide range of dynamical behaviours depending on the system size, its geometry, the boundary conditions and the perturbation itself. Examples encompass viscous fingering instabilities [8][9][10][11][12], wrinkling and buckling [13][14][15], elastocapillary rise [16], dewetting-like rim formation due to attractive van der Waals forces [17], biologically induced membrane adhesion [18,19], flow induced by applied pressure fields [20], including wake formation [21], and peristaltic flow in cylindrical geometries [22,23].…”