Modelling tubular shapes in the inner mitochondrial membrane

TL;DR

This paper presents a thermodynamic model explaining the formation of tubular structures in the inner mitochondrial membrane, predicting a pressure difference and lipid composition variations based on membrane shape and lipid types.

Contribution

It introduces a novel thermodynamic model accounting for tubular membrane structures with specific lipid compositions and predicts measurable physical and chemical differences.

Findings

Pressure difference of 0.2 atmospheres across the membrane.

Lipid migration causes about 7% concentration variation.

Model explains observed tubule radius of 10 nm.

Abstract

The inner mitochondrial membrane has been shown to have a novel structure that contains tubular components whose radii are on the order of 10 nm as well as comparatively flat regions. The structural organization of mitochondria is important to understanding their functionality. We present a model that can account, thermodynamically, for the observed size of the tubules. The model contains two lipid constituents with different shapes. They are allowed to distribute in such a way that the composition differs on the two sides of the tubular membrane. Our calculations make two predictions: (1) there is a pressure difference of 0.2 atmospheres across the inner membrane as a necessary consequence of the experimentally observed tubule radius of 10 nm. and (2) migration of differently shaped lipids causes concentration variations between the two sides of the tubular membrane on the order of 7 percent.