(Springer) Nature's way of allowing proteins across its gates, through porous biological membranes, depends, among others, on their electrical charge. In a new study published in EPJ E, Albert Johner from the Charles Sadron Institute in Strasbourg, France and Jean-Francois Joanny from ESPCI Paris have uncovered how the mixed electrical charge at the ends of proteins can influence biological membrane crossing. This has potential implications for our understanding of how proteins travel across the body, and of disease mechanisms.