His protein coils tightened. Whump. His shape flipped inside out.
Pump-O, now shaped like an open claw facing outward, had a new hunger: potassium. Two weary potassium ions, shivering in the cold exterior, saw the open binding sites and leaped in. primary active transport
The three sodium ions, who had been clinging to his interior binding sites, suddenly found themselves facing the outside world. They were ejected with a surprised “Hey!” into the extracellular fluid. His protein coils tightened