The calcium pump is only a few nanometers long in each direction and exists in the cell membrane. However, although it is small, it is a necessity of life. Calcium pump is the reason why our muscles can contract and neurons can send signals. If this tiny calcium pump stops working, the communication between cells will stop. This is why cells consume so much energy-about a quarter of the fuel called ATP in the body-to keep these calcium pumps running.

We still know little about the structure and function of this important calcium pump. Understanding this kind of calcium pump is very important for understanding the energy balance and other important functions in the body.

In a new study, researchers from Denmark, the United States and the United Kingdom showed for the first time how the calcium pump works at the single molecule level and how it ensures that ions are pumped in one direction. The related research results were published in the journal Nature in October1711610, entitled "Transport Kinetics of P-ATPase Revealed by Single Molecule fret". The authors of this paper are Paul Nissen of Aarhus University in Denmark and Scott C. blanchard of Cornell University in the United States.

Molecular basis

A key point of this new study involves unidirectional ion transport. Prior to this, it was thought that the unidirectional transport of calcium pump was produced by cutting ATP molecules rich in energy. The hypothesis is that when ATP is cut off, the calcium pump can't go back to form ATP again. Facts have proved that this assumption is incorrect.

Dr Fellow Mateusz Dyla, the first author of the paper, said, "In the pumping cycle, we have determined a new closed state. Only when calcium ions come from intracellular fluid's body can this calcium pump enter this pumping cycle and cut ATP. If the calcium ion comes from the environment in which the cell is located, then the calcium pump cannot enter this closed state. When calcium ions are released from this state, they are in a state where they can only enter and cannot retreat. It is this mechanism that explains the function of this calcium pump as a pump, rather than just passively transporting ion channels. This unique insight is based on highly advanced experiments. These experiments let us observe for the first time that this calcium pump performs its function. "

This calcium pump needs energy, which is obtained from its cleavage of ATP molecules. The released energy is converted into the operation of the calcium pump. This explains that there is a very large concentration gradient inside and outside the cell. This concentration difference can exceed 6,543.8+0,000 times, which is very important for cell-to-cell communication (such as nerve signal transduction).