Na/K pump which enzyme is used -

Sodium-potassium pump is the most important pump for primary active transport Q in the body. Na + -K + pump is an electrogenic pump Q that is responsible for maintaining the Na + and K + concentration difference across the cell membrane. Na + - K + pump extrudes 3 Na + out from the cell and at the same time pump 2K + into the cell Q , i.e., Coupling ratio of Na + K + pump is 3 : 2 Q . Na + and K + transport by Na + - K + pump is primary active transport Q and both Na + and K + are transported against concentration gradient Q (intracellular fluid has high concentration of K + and ECF has high concentration of Na - ). Na + K + pump uses energy by hydrolysing ATP; this pump contains ATPase activity Q. Na + - K + pump is a carrier protein which is a heterodimer 0 made up of two separate globular proteins: a larger one called α-subunit with a molecular weight of 100,000 and a smaller one called β-subunit, with a molecular weight of about 55,000. Both α- and β- subunits span across the membrane with intracellular and extracellular sites.  Na + and K + transport occurs through a-subunits. Intracellular portion of a-subunit has three Na + binding sites (three receptor sites for Na + ), an ATP binding site, a phosphorylating site and ATPase activity Q. Extracellular portion Q has two K + binding sites (two receptor sites for K + ), and an ouabain binding site Q. The β- subunit has three extracellular glycosylation sites Q, all of which appear to have attached carbohydrate residue. The Na + - K + pump is an electrogenic pump Q since it produces a net movement of positive charge out of the cell. Thus, besides maintaining the ionic composition of the intracellular fluid, the Na + - K + pump helps to maintain the electrochemical potential difference across the cell membrane. However, Na + - K + pump contributes only 4 millivolts to the total resting membrane potential of 90 volts which is almost negligible Q. Active transport of Na+ and K+ - is one of the major energy-using processes in the body. On average, it accounts for about 24% of the energy utilized by cell and in neurons, it accounts for 70%. o Activity of Na+ - K+ pump is stimulated by the increased intracellular concentration of Na +, thyroid hormones, aldosterone and insulin. Pump activity is inhibited by CHF, CRF, digoxin toxicity and dopamine.