His protein coils tightened. Whump. His shape flipped inside out.
And that was it. One cycle. Three sodiums out. Two potassiums in. One ATP sacrificed. primary active transport
Pump-O just reset his shape, cracked his knuckles again, and waited for the next ATP to wander by. “Kid,” he muttered to a passing glucose molecule, “that’s what primary means. No shortcuts. No following the crowd. I burn the fuel. I make the gradient. I am the source.” His protein coils tightened
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. And that was it
That energy didn't heat the place up or light a bulb. It did something far stranger: it twisted Pump-O’s very soul.
Pump-O didn't do equilibrium. He did work .
Another twist—this time, the phosphate group that had been stuck to Pump-O fell off, and the protein relaxed back to its original shape. The two potassium ions were dumped, grateful and warm, into the crowded cytoplasm.
