# Membrane morphologies induced by arc-shaped scaffolds are determined by arc angle and coverage

## TL;DR

This study uses modeling and simulations to explore how arc-shaped scaffolds influence membrane shapes, revealing that coverage and arc angle critically determine whether tubules or stacks form.

## Contribution

It systematically analyzes the effects of arc angle and coverage on membrane morphology, providing new insights into membrane shaping mechanisms by proteins.

## Key findings

- Membrane tubules form at coverages above 40%, regardless of arc angle.
- Intermediate coverages depend on the arc angle, affecting membrane shape.
- Arc angles over 120 degrees induce double-membrane stacks at certain coverages.

## Abstract

The intricate shapes of biological membranes such as tubules and membrane stacks are induced by proteins. In this article, we systematically investigate the membrane shapes induced by arc-shaped scaffolds such as proteins and protein complexes with coarse-grained modeling and simulations. We find that arc-shaped scaffolds induce membrane tubules at membrane coverages larger than a threshold of about 40%, irrespective of their arc angle. The membrane morphologies at intermediate coverages below this tubulation threshold, in contrast, strongly depend on the arc angle. Scaffolds with arc angles of about 60 degree akin to N-BAR domains do not change the membrane shape at coverages below the tubulation threshold, while scaffolds with arc angles larger than about 120 degree induce double-membrane stacks at intermediate coverages. The scaffolds stabilize the curved membrane edges that connect the membrane stacks, as suggested for complexes of reticulon proteins. Our results provide general insights on the determinants of membrane shaping by arc-shaped scaffolds.