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BIOL211 Cell Biology > Primary Pumps > Flashcards

Primary Pumps Flashcards

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1
Q

What do P-type ATPases pump?
Give examples

A

Cations
K+ Na+ Ca2+ H+ Mg+

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2
Q

What are P-type ATPases inhibited by?

A

Micromolar amounts of orthovanadate

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3
Q

How does orthovanadate affect P-type ATPases?

A

Inhibits them by working in the same way, preventing phosphorylation

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4
Q

delete

A

delete

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5
Q

Where do you find Na+/K+ ATPase in animal cells?

A

In most plasma membranes of animal cells

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6
Q

How many isoforms does the Na+/K+ ATPase pump have?

A

3 isoforms

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7
Q

What are the general functions of Na+/K+ ATPase?

A

Maintaining high K+ and low Na+ in the cytosol

Maintains Na+ electrochemical potential via Na+ coupled transport

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8
Q

What happens if Na+ builds up inside a cell?

A

It is toxic to the cell

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9
Q

What is the stoichemetry of Na+/K+ ATPase pumps?

A

3 Na+ and 2 K+ per ATP hydrolysed

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10
Q

What is the general structure of a Na+/K+ ATPase?

A

2 alpha (112kDa) and 2 beta (34 kDa) subunits

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11
Q

Where do we find H+ ATPases?

A

All plasma membranes of plant and fungal cells

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12
Q

Stoichiometry of H+ ATPases?

A

1H+ for every ATP hydrolysed

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13
Q

Functions of H+ ATPase pumps:

A

Expel excess H+ produced during metabolism
Generate H+ electrochemical gradient used to drive H+ coupled transport
Maintain negative transmembrane voltage (> - 200 mV)
Regulate cytosolic pH
Acidification of extracellular medium (loosen cell walls to allow cell to expand using vacuoles)

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14
Q

What is the structure of a H+ ATPase pump?

A

1 alpha (112 kDa) subunit

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15
Q

What does SERCA stand for?

A

Sarcoplasmic endoreticulum Ca2+ ATPase

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16
Q

Where are SERCA found?

A

Sarcoplasmic reticulum network of tubules storing Ca2+ in the muscle cell cytoplasm

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17
Q

Stoichiometry of SERCA?

A

2Ca2+ per ATP hydrolysed

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18
Q

Function of SERCA?

A

Restore low cytosolic Ca2+ after muscle contraction

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19
Q

Structure of SERCA

A

1 alpha subunit (3 isoforms)

20
Q

Inhibitor of SERCA?

A

Thapsigargin

21
Q

What does PMCA stand for?

A

Plasma membrane Ca2+ ATPase

22
Q

Where are PMCA found?

A

Fungal, plant and animal plasma membranes

23
Q

Function of PMCA?

A

Maintain low cytosolic Ca2+ (high cytosolic Ca2+ is cytotoxic)
Central role in cell signalling

24
Q

Structure of PMCA?

A

1 alpha subunit

25
Q

Stoichiometry of PMCA?

A

Swaps 1 - 2 Ca2+ for a H+ per ATP

26
Q

Where do you find H+/K+ ATPase?

A

Plasma membrane of gastric epithelium cells (stomach wall)

27
Q

Function of H+/K+ ATPase

A

H+ secretion in to the lumen of the stomach to maintain acidic environment (=0.16 M HCl)

28
Q

Structure of H+/K+ pump

A

2 alpha and 2 beta subunits

29
Q

Stiochiometry of gastric muscosal H+/K+ ATPase?

A

2K+ for 2H+ per ATP

30
Q

What is the function of CPx pumps?

A

Work similarly to P-type pumps, but target toxic transition metals that disrupt normal physiological functions

31
Q

What kind of toxic transition metals do CPx pumps target?

A

Cu, Pb, Cd, Zn

(Copper, lead, cadmium, zinc)

32
Q

What disease is associated with systemic copper deficiency?

A

Menkes disease (neurological disease, neurones don’t have enough copper)

33
Q

What disease is associated with excessive copper accumulation in the liver?

A

Wilsons disease

34
Q

If someone is suffering from Wilsons or Menkes disease, what do they likely have a problem with?

A

CPx pumps, which target transition metals such, as in this case, copper

35
Q

What does the COPA pump do?

A

Pumps out excess copper (copper can be toxic to cells)

36
Q

What does the COPB pump do?

A

Pumps in copper when the cell is deficient in it

37
Q

Why is the pump named CPx ?

A

Amino acid motif of cysteine, proline and either cysteine, histidine or serine

38
Q

Why are the cysteine repeats important in a CPx pump?

A

To stabilise the binding of the transition metal the pump is trying to transport

39
Q

What is the purpose of region B in CPx pumps and P-type ATPases?

A

Induces conformational changes in ion binding site

40
Q

What is the purpose of region C in CPx pumps and P-type ATPases?

A

Phosphorylation site and nucleotide binding site

41
Q

What is the purpose of region J in CPx pumps and P-type ATPases?

A

Hinge to allow cytosolic regions to move and interact
Allows protein to flex to expose binding sites to ions, one side to the other

42
Q

What is the main function of V-type pumps?

A

To generate the H+ electrochemical gradient required across intracellular membranes for associated carriers to fulfil their function

(eg; for an antiporter requiring H+ to transport a neurotransmitter across a vesicle membrane to store it in that vesicle)

43
Q

Give an example for what might be powered by a V-type pump in animal cells

A

An antiporter requiring H+ to transport a neurotransmitter across a vesicle membrane to store it in that vesicle

44
Q

What is the main purpose of the ABC transporters?

A

Use energy from ATP hydrolysis to transport a wide variety of solutes in or out of the cell, allowing it to acquire nutrients or get rid of toxins or drugs

45
Q

What are MDR transporters?

A

“Multiple drug resistance” allow cell to pump toxins or drugs out of them, problematic in pathogenic or cancerous cells as it makes them resistant to these drugs/treatments (so some drugs target these transporters)

46
Q

What causes cystic fibrosis?

A

An ABC transporter wrongly acts as an ATP-gated ion channel / transporter for chloride ions

47
Q
A

BIOL211 Cell Biology (19 decks)

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