Subject: How to calculate protein spreading area on a membrane over time using GROMACS and Martini 3

Dear GROMACS and Martini users,

I am working with a membrane-protein system using the Martini 3 force field and would like to calculate the time-dependent spreading area of a protein (or protein condensate) on the membrane surface. Specifically, I want to quantify how the protein’s footprint on the membrane evolves during the simulation. Could anyone suggest robust methods or tools for this analysis?

Here is some context:

  • Force field: Martini 3

  • MD engine: GROMACS

  • System: A protein/condensate interacting with a lipid bilayer (e.g., DIPC/DIPS)

  • Goal: Obtain a curve of protein projected area on the XY (membrane) plane vs. time

I am aware of the general principle: project the protein atoms along the membrane normal (Z-axis) and calculate the area they occupy on the XY plane. However, I am looking for practical implementations, preferably ones that work well with Martini 3 systems.

I would greatly appreciate any advice, tool recommendations, or shared scripts.

Thank you in advance for your help!