The sodium-potassium pump (sodium potassium pump), also known as sodium-potassium pump, it caused the cells to NA + concentration higher than the cell through the cell membrane NA + along the concentration difference into the cell, the transporter protein by the body would not be easy substance to the common transport into cells.
principle sodium potassium pump (also known as sodium and potassium transporters), the protein molecule, the exchange between sodium and potassium ions. Whenever the three sodium ions are transferred to
rolehigh potassium inside the cell is the number of metabolic reactions necessary conditions; prevent cell edema; potential energy reserve.
composition and mode of action
compositionthe Na-K pump is driven by the α, β subunits. α subunit molecular weight of to 120KD the transmembrane protein, both Na, K binding sites, but also with the ATPase activity and Na-K pump, also known as Na-K-ATP enzyme. β subunit of the small subunit is a glycoprotein of molecular weight of about 50KD.
is generally believed that the Na-K pump is the first film the inside of the intracellular Na combined with the ATP enzyme activity is activated, the energy released by ATP hydrolysis to "pump" the conformational change of the Na output cells ; At the same time, the "pump" and the cell membrane outside of the K dephosphorylation occurs after the conformational change, again the K input cells. Studies have shown that each consume an ATP molecule, allows cells to reduce 3 Na and increase 2 K.
membrane sodium-potassium pump role first and foremost by Hodkin and Keynes (1955) .1957 years Skou discovered Na +-K + ATP enzyme and prove it with the role of sodium-potassium pump.
mode of actionmode of action of the sodium-potassium pump can be due to different physiological conditions vary in the red cell membrane may have the following ways:
1. normal mode of action - the use of ATP hydrolysis of Na +-K + transmembrane transport coupling.
2. pump the opposite direction - using the Na +-K + transmembrane transport to promote the synthesis of ATP.
3. Na + - Na + exchange reaction may be related to ATP and ADP exchange reaction phase coupling.
4. K + - K + exchange reaction with Pi and H2 (18) O exchange reaction coupling.
5. dependent on ATP hydrolysis, uncoupling the Na + discharge.
works and roles Na +-K + pump - in fact, Na +-K + ATP enzyme, present in the action, the plant cytoplasmic membrane, it has a size of two subunits, the large subunit catalytic ATP hydrolysis, the small subunit is a glycoprotein of Na +-K + ATP enzyme by phosphorylation and dephosphorylation processes occurrence of the conformation of the changes leading to Na +, K, + the affinity changes of the large subunit to affinity of Na +-state combination of Na + after, trigger hydrolysis of ATP per hydrolysis of one ATP release of energy transportation to 3 of Na + into the cell, at the same time uptake of two K + into the cell, resulting in the transmembrane gradient and potential difference which the transmission of nerve impulses especially important, caused by of Na +-K + pump membrane potential difference accounted for about 80% of the entire nerve membrane voltage of. If the purification of Na + the-K + pump assembly in the red cell membrane vesicles (blood film), to artificially increase the membrane on both sides of the of Na +, K, + gradient to a certain extent, gradient held by some of the energy greater than the ATP hydrolysis of the chemical energy, Na +, K, + will reverse cis concentrated poor flow through of Na +-K, + pump, and synthesis of ATP.
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