Primary Active Transport Access

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.

Pump-O just smiled. Or rather, he shifted his shape into something resembling a smile. Then he stomped his foot, signaling his true partner in crime: , the cell’s high-energy currency. primary active transport

His protein coils tightened. Whump. His shape flipped inside out. Another twist—this time, the phosphate group that had