Cell membrane sodium-potassium pump The first membrane-bound sodium-potassium pump was discovered by Hodkin and Keynes (1955). In 1957, Skou discovered Na + -K + ATPase and demonstrated its association with sodium-potassium pump action Depending on different physiological conditions, there may be several ways in the erythrocyte membrane: 1. The normal mode of action - coupled with the transmembrane transport of Na + -K + using ATP in aqueous media. 2. The opposite direction of the pump - Adopting the transmembrane transport of Na + -K + to promote the synthesis of ATP. 3.Na + - Na + exchange reaction may be coupled with ATP and ADP exchange reaction.4.K + - K + exchange reaction with Pi and H2 (18) O Exchange reaction phase coupling.5 rely on ATP hydrolysis, uncoupling Na + excretion Na-K pump by α, β two subunits. The α-subunit is a transmembrane protein with a molecular weight of about 120 kD. It has both Na and K binding sites and ATPase activity. Na-K pump is also called Na-K-ATPase. The β subunit is a small subunit that is a glycoprotein with a molecular weight of about 50KD. It is generally believed that the Na-K pump binds to intracellular Na at the inner side of the membrane first. After the ATPase activity is activated, the energy released by ATP hydrolysis changes the conformation of the "pump" itself and outputs Na out of the cell. Meanwhile, the "pump" Conjugate with K on the outside of the cell membrane, the conformation changes again after dephosphorylation, and K is input into the cell. Studies show that for each ATP molecule consumed, 3 Na can be decreased and 2 K can be added to the cell.
The heartwood is yellow-brown and becomes red-brown with air. The sapwood is clearly demarcated. The grain is interlocked and the texture is medium.
Okan is very durable to fungi and is durable to dry wood borers; sapwood demarcated (risk limited to sapwood). Due to its high specific gravity and hardness, this species naturally covers the biological hazard class 5 (end-uses in the marine environment or in brackish water).
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