P-type pumps Essay

Question 1

What are P-type ATPases inhibited by?

Answer 1

Micromolar amounts of orthovanadate

Question 2

How does the P-type ATPase inhibitor inhibit ATPase action?

Answer 2

It acts as a competitive inhibitor and prevents a conformational change in the structure of ATPase

Question 3

How does ATP hydrolysis and the phosphorylation of aspartate change the 3D structure of P-type ATPase?

Answer 3

ATP hydrolysis and phosphorylation of the aspartate results in the movement of the head regions and this conformational change (from E1 to E2) alters the affinity of the binding site and exposes the binding site to the lumen if the r sarcoplasmic reticulum (hence ion translocation).

Question 4

What is the stoichiometry for Na/K pumps in animal cells

Answer 4

3 Na+ and 2 K+ for every ATP hydrolysed

Question 5

What is the role of Na/K ATPase pumps in animal cells?

Answer 5

Maintain high levels of K+ and low levels of Na+

Also maintains Na+ electrochemical potential for Na+ coupled transport

Question 6

What is the stoichiometry of the H+ ATPase pump found in plant and fungal cells?

Answer 6

1 H+ per ATP hydrolysed

Question 7

What’s the role of the H+ ATPase in fungal and plant cells

Answer 7

Expels excess H+ produced during metabolism and generate a H+ electrochemical gradient which is used to drive H+ couple transport
It maintains negative transmembrane voltage and regulates cytosolic pH
Acidification of extracellular medium loosen cells walls

Question 8

What do the stoichiometry of Ca2+ ATPase in sarcoplasmic endoreticulum

Answer 8

2 Ca2+ for every ATP hydrolysed

Question 9

What is the role of the Ca2+ ATPase in sarcoplasmic endoreticulum

Answer 9

Restore low levels of cytosolic Ca2+ after muscle contraction

Question 10

What is the structure of the Ca2+ ATPase found in sarcoplasmic endoreticulum ?

Answer 10

1 alpha subunit (with 3 isoforms)

Question 11

What is the stoichiometry of Ca2+ ATPase found in plasma membranes

Answer 11

1-2 Ca2+ per ATP hydrolysed

Question 12

What is the role of the Ca2+ ATPase in plasma membranes?

Answer 12

Maintain low cytosolic Ca2+ levels

Question 13

What is the structure of the Ca2+ ATPase in plasma membranes

Answer 13

1 alpha subunit

Question 14

What is the stoichiometry of H/K ATPase on gastric epithelium cells?

Answer 14

2H+:2K+ per ATP hydrolysed

Question 15

What is the role of the H/K ATPase found in gastric epithelium cells?

Answer 15

Secrete H+ into the lumen do the stomach and maintain h to e acidic stomach of a pH of 7.4

Question 16

What is the structure of the H+/K+ ATPase in gastric epithelium cells?

Answer 16

2 alpha and 2 beta subunits