Geometric and Electromagnetic Aspects of Fusion Pore Making

TL;DR

This paper models the formation of fusion pores in regulated exocytosis, analyzing the membrane morphology and electromagnetic influences to explain energy efficiency and flickering phenomena.

Contribution

It introduces a novel free boundary problem model for fusion pore formation and links electromagnetic fields to exocytosis dynamics.

Findings

Explains energy-efficient dimple formation prior to fusion.

Relates exocytosis timing to electromagnetic wave properties.

Accounts for flickering in secretion processes.

Abstract

For regulated exocytosis, we model the morphology and dynamics of the making of the fusion pore or porosome as a cup-shaped lipoprotein structure (a dimple or pit) on the cytosol side of the plasma membrane. We describe the forming of the dimple by a free boundary problem. We discuss the various forces acting and analyze the magnetic character of the wandering electromagnetic field wave produced by intracellular spatially distributed pulsating (and well observed) release and binding of calcium ions anteceding the bilayer membrane vesicle fusion of exocytosis. Our approach explains the energy efficiency of the observed dimple forming prior to hemifusion and fusion pore, and the observed flickering in secretion. It provides a frame to relate characteristic time length of exocytosis to the frequency, amplitude and direction of propagation of the underlying electromagnetic field wave.