In spite of our observations, Martini 3 has been shown to successfully model helix association and the salting-in/saltingout effect of proteins in solution . However, in those validation systems helix association was probed only for TM peptides/proteins; the protein-protein interaction imbalances at play in our tests may be mitigated in a membrane environment, as they already sometimes were in Martini 2 . The salting-in/salting-out Martini 3 tests, however, were performed in solution, and yielded realistic degrees of aggregation for the villin headpiece (VH) and the mutated cellulose-binding domain from Cellulomonas fimi (CBD) . Those proteins are only a few kDa larger than the coiled coil dimers in this work but are large enough to have well-defined tertiary structure and globular shape. This makes for larger interaction patches when oligomerizing compared to the almost linear interface between two single α-helices, and may compensate the factors that prevent Martini 3 from properly forming the short coiled coils. Additionally, neither VH nor CBD are fully αhelical/β-sheet structures (helices/sheets account for 70% and 57% of VH and CBD, respectively). If indeed backbone beads are overly polar in Martini 3 α-helices and β-sheets, the relative inaccuracy in overall protein hydrophilicity would then be greater in the 100% helical coiled coil peptides than in VH or CBD. If correct, our explanatory hypotheses for the lack of oligomerization would point to short, fully helical peptides as extreme cases for which Martini 3 selectivity breaks down.