2 research outputs found
Ion pump activity generates fluctuating electrostatic forces in biomembranes
We study the non-equilibrium dynamics of lipid membranes with proteins that
actively pump ions across the membrane. We find that the activity leads to a
fluctuating force distribution due to electrostatic interactions arising from
variation in dielectric constant across the membrane. By applying a multipole
expansion we find effects on both the tension and bending rigidity dominated
parts of the membranes fluctuation spectrum. We discuss how our model compares
with previous studies of force-multipole models.Comment: 6 pages, 2 figures, to appear in EP
Fluctuations in active membranes
Active contributions to fluctuations are a direct consequence of metabolic
energy consumption in living cells. Such metabolic processes continuously
create active forces, which deform the membrane to control motility,
proliferation as well as homeostasis. Membrane fluctuations contain therefore
valuable information on the nature of active forces, but classical analysis of
membrane fluctuations has been primarily centered on purely thermal driving.
This chapter provides an overview of relevant experimental and theoretical
approaches to measure, analyze and model active membrane fluctuations. In the
focus of the discussion remains the intrinsic problem that the sole fluctuation
analysis may not be sufficient to separate active from thermal contributions,
since the presence of activity may modify membrane mechanical properties
themselves. By combining independent measurements of spontaneous fluctuations
and mechanical response, it is possible to directly quantify time and
energy-scales of the active contributions, allowing for a refinement of current
theoretical descriptions of active membranes.Comment: 38 pages, 9 figures, book chapte